[SPARK-5167][SQL] Move Row into sql package and make it usable for Java.

Mostly just moving stuff around. This should still be source compatible since we type aliased Row previously in org.apache.spark.sql.Row.

Added the following APIs to Row:
```scala
def getMap[K, V](i: Int): scala.collection.Map[K, V]
def getJavaMap[K, V](i: Int): java.util.Map[K, V]
def getSeq[T](i: Int): Seq[T]
def getList[T](i: Int): java.util.List[T]
def getStruct(i: Int): StructType
```

Author: Reynold Xin <rxin@databricks.com>

Closes #4030 from rxin/sql-row and squashes the following commits:

6c85c29 [Reynold Xin] Fixed style violation by adding a new line to Row.scala.
82b064a [Reynold Xin] [SPARK-5167][SQL] Move Row into sql package and make it usable for Java.

sql/catalyst/src/main/java/org/apache/spark/sql/RowFactory.java

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql;
+
+import org.apache.spark.sql.catalyst.expressions.GenericRow;
+
+/**
+ * A factory class used to construct {@link Row} objects.
+ */
+public class RowFactory {
+
+  /**
+   * Create a {@link Row} from an array of values. Position i in the array becomes position i
+   * in the created {@link Row} object.
+   */
+  public static Row create(Object[] values) {
+    return new GenericRow(values);
+  }
+}

sql/catalyst/src/main/scala/org/apache/spark/sql/Row.scala

@@ -0,0 +1,240 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql
+
+import org.apache.spark.sql.catalyst.expressions.GenericRow
+
+
+object Row {
+  /**
+   * This method can be used to extract fields from a [[Row]] object in a pattern match. Example:
+   * {{{
+   * import org.apache.spark.sql._
+   *
+   * val pairs = sql("SELECT key, value FROM src").rdd.map {
+   *   case Row(key: Int, value: String) =>
+   *     key -> value
+   * }
+   * }}}
+   */
+  def unapplySeq(row: Row): Some[Seq[Any]] = Some(row)
+
+  /**
+   * This method can be used to construct a [[Row]] with the given values.
+   */
+  def apply(values: Any*): Row = new GenericRow(values.toArray)
+
+  /**
+   * This method can be used to construct a [[Row]] from a [[Seq]] of values.
+   */
+  def fromSeq(values: Seq[Any]): Row = new GenericRow(values.toArray)
+}
+
+
+/**
+ * Represents one row of output from a relational operator.  Allows both generic access by ordinal,
+ * which will incur boxing overhead for primitives, as well as native primitive access.
+ *
+ * It is invalid to use the native primitive interface to retrieve a value that is null, instead a
+ * user must check `isNullAt` before attempting to retrieve a value that might be null.
+ *
+ * To create a new Row, use [[RowFactory.create()]] in Java or [[Row.apply()]] in Scala.
+ *
+ * A [[Row]] object can be constructed by providing field values. Example:
+ * {{{
+ * import org.apache.spark.sql._
+ *
+ * // Create a Row from values.
+ * Row(value1, value2, value3, ...)
+ * // Create a Row from a Seq of values.
+ * Row.fromSeq(Seq(value1, value2, ...))
+ * }}}
+ *
+ * A value of a row can be accessed through both generic access by ordinal,
+ * which will incur boxing overhead for primitives, as well as native primitive access.
+ * An example of generic access by ordinal:
+ * {{{
+ * import org.apache.spark.sql._
+ *
+ * val row = Row(1, true, "a string", null)
+ * // row: Row = [1,true,a string,null]
+ * val firstValue = row(0)
+ * // firstValue: Any = 1
+ * val fourthValue = row(3)
+ * // fourthValue: Any = null
+ * }}}
+ *
+ * For native primitive access, it is invalid to use the native primitive interface to retrieve
+ * a value that is null, instead a user must check `isNullAt` before attempting to retrieve a
+ * value that might be null.
+ * An example of native primitive access:
+ * {{{
+ * // using the row from the previous example.
+ * val firstValue = row.getInt(0)
+ * // firstValue: Int = 1
+ * val isNull = row.isNullAt(3)
+ * // isNull: Boolean = true
+ * }}}
+ *
+ * Interfaces related to native primitive access are:
+ *
+ * `isNullAt(i: Int): Boolean`
+ *
+ * `getInt(i: Int): Int`
+ *
+ * `getLong(i: Int): Long`
+ *
+ * `getDouble(i: Int): Double`
+ *
+ * `getFloat(i: Int): Float`
+ *
+ * `getBoolean(i: Int): Boolean`
+ *
+ * `getShort(i: Int): Short`
+ *
+ * `getByte(i: Int): Byte`
+ *
+ * `getString(i: Int): String`
+ *
+ * In Scala, fields in a [[Row]] object can be extracted in a pattern match. Example:
+ * {{{
+ * import org.apache.spark.sql._
+ *
+ * val pairs = sql("SELECT key, value FROM src").rdd.map {
+ *   case Row(key: Int, value: String) =>
+ *     key -> value
+ * }
+ * }}}
+ *
+ * @group row
+ */
+trait Row extends Seq[Any] with Serializable {
+  def apply(i: Int): Any
+
+  /** Returns the value at position i. If the value is null, null is returned. */
+  def get(i: Int): Any = apply(i)
+
+  /** Checks whether the value at position i is null. */
+  def isNullAt(i: Int): Boolean
+
+  /**
+   * Returns the value at position i as a primitive int.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getInt(i: Int): Int
+
+  /**
+   * Returns the value at position i as a primitive long.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getLong(i: Int): Long
+
+  /**
+   * Returns the value at position i as a primitive double.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getDouble(i: Int): Double
+
+  /**
+   * Returns the value at position i as a primitive float.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getFloat(i: Int): Float
+
+  /**
+   * Returns the value at position i as a primitive boolean.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getBoolean(i: Int): Boolean
+
+  /**
+   * Returns the value at position i as a primitive short.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getShort(i: Int): Short
+
+  /**
+   * Returns the value at position i as a primitive byte.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getByte(i: Int): Byte
+
+  /**
+   * Returns the value at position i as a String object.
+   * Throws an exception if the type mismatches or if the value is null.
+   */
+  def getString(i: Int): String
+
+  /**
+   * Return the value at position i of array type as a Scala Seq.
+   * Throws an exception if the type mismatches.
+   */
+  def getSeq[T](i: Int): Seq[T] = apply(i).asInstanceOf[Seq[T]]
+
+  /**
+   * Return the value at position i of array type as [[java.util.List]].
+   * Throws an exception if the type mismatches.
+   */
+  def getList[T](i: Int): java.util.List[T] = {
+    scala.collection.JavaConversions.seqAsJavaList(getSeq[T](i))
+  }
+
+  /**
+   * Return the value at position i of map type as a Scala Map.
+   * Throws an exception if the type mismatches.
+   */
+  def getMap[K, V](i: Int): scala.collection.Map[K, V] = apply(i).asInstanceOf[Map[K, V]]
+
+  /**
+   * Return the value at position i of array type as a [[java.util.Map]].
+   * Throws an exception if the type mismatches.
+   */
+  def getJavaMap[K, V](i: Int): java.util.Map[K, V] = {
+    scala.collection.JavaConversions.mapAsJavaMap(getMap[K, V](i))
+  }
+
+  /**
+   * Return the value at position i of struct type as an [[Row]] object.
+   * Throws an exception if the type mismatches.
+   */
+  def getStruct(i: Int): Row = getAs[Row](i)
+
+  /**
+   * Returns the value at position i.
+   * Throws an exception if the type mismatches.
+   */
+  def getAs[T](i: Int): T = apply(i).asInstanceOf[T]
+
+  override def toString(): String = s"[${this.mkString(",")}]"
+
+  /**
+   * Make a copy of the current [[Row]] object.
+   */
+  def copy(): Row
+
+  /** Returns true if there are any NULL values in this row. */
+  def anyNull: Boolean = {
+    val l = length
+    var i = 0
+    while (i < l) {
+      if (isNullAt(i)) { return true }
+      i += 1
+    }
+    false
+  }
+}

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/package.scala

@@ -49,6 +49,10 @@ package org.apache.spark.sql.catalyst
  */
 package object expressions  {
 
+  type Row = org.apache.spark.sql.Row
+
+  val Row = org.apache.spark.sql.Row
+
   /**
    * Converts a [[Row]] to another Row given a sequence of expression that define each column of the
    * new row. If the schema of the input row is specified, then the given expression will be bound