dataset: remove customdb implementation

The customdb database was a failed attempt to implement a simple way of
efficiently extracting bounding boxes from planet files.  It was written
before the pgsimple and pgsnapshot implementations (if memory serves
correctly).  It is unlikely to have been used in the wild, so I'm
removing the code.

osmosis-dataset/src/main/java/org/openstreetmap/osmosis/dataset/DatasetPluginLoader.java

@@ -1,15 +1,13 @@
 // This software is released into the Public Domain.  See copying.txt for details.
 package org.openstreetmap.osmosis.dataset;
 
-import java.util.HashMap;
-import java.util.Map;
-
 import org.openstreetmap.osmosis.core.pipeline.common.TaskManagerFactory;
 import org.openstreetmap.osmosis.core.plugin.PluginLoader;
 import org.openstreetmap.osmosis.dataset.v0_6.DatasetBoundingBoxFilterFactory;
 import org.openstreetmap.osmosis.dataset.v0_6.DumpDatasetFactory;
-import org.openstreetmap.osmosis.dataset.v0_6.ReadDatasetFactory;
-import org.openstreetmap.osmosis.dataset.v0_6.WriteDatasetFactory;
+
+import java.util.HashMap;
+import java.util.Map;
 
 
 /**
@@ -28,18 +26,12 @@ public Map<String, TaskManagerFactory> loadTaskFactories() {
 
 		factoryMap = new HashMap<String, TaskManagerFactory>();
 
-		factoryMap.put("write-customdb", new WriteDatasetFactory());
-		factoryMap.put("wc", new WriteDatasetFactory());
 		factoryMap.put("dataset-dump", new DumpDatasetFactory());
 		factoryMap.put("dd", new DumpDatasetFactory());
-		factoryMap.put("read-customdb", new ReadDatasetFactory());
-		factoryMap.put("rc", new ReadDatasetFactory());
 		factoryMap.put("dataset-bounding-box", new DatasetBoundingBoxFilterFactory());
 		factoryMap.put("dbb", new DatasetBoundingBoxFilterFactory());
 
-		factoryMap.put("write-customdb-0.6", new WriteDatasetFactory());
 		factoryMap.put("dataset-dump-0.6", new DumpDatasetFactory());
-		factoryMap.put("read-customdb-0.6", new ReadDatasetFactory());
 		factoryMap.put("dataset-bounding-box-0.6", new DatasetBoundingBoxFilterFactory());
 
 		return factoryMap;