Partly revert 84d4854 (#923)

This partly reverts some changes of 84d4854, by saving / restoring tty
stuff right before and after reading input. This basically runs
processes right before and after reading input, which incurs a perf cost
- just like before 84d4854.

One can see it by starting an Ammonite session, waiting for it to be
fully started, then repeatedly entering Enter. There's a small delay
between each prompt. 84d4854 addressed that, but breaking a few stuff
along the way (#920, #922).

amm/repl/src/main/scala/ammonite/repl/Repl.scala

@@ -184,13 +184,7 @@ class Repl(input: InputStream,
 
 
   def run(): Any = {
-
-    val initialConfigOpt =
-      if (scala.util.Properties.isWin)
-        None
-      else
-        Some(ammonite.terminal.TTY.init())
-
+    welcomeBanner.foreach(printer.outStream.println)
     @tailrec def loop(): Any = {
       val actionResult = action()
       remoteLogger.foreach(_.apply("Action"))
@@ -208,15 +202,8 @@ class Repl(input: InputStream,
         case Some(value) => value
       }
     }
-
-    try {
-      welcomeBanner.foreach(printer.outStream.println)
-      loop()
-    } finally {
-      for (config <- initialConfigOpt)
-        ammonite.terminal.TTY.stty(config)
-    }
-}
+    loop()
+  }
 
   def beforeExit(exitValue: Any): Any = {
     Function.chain(interp.beforeExitHooks)(exitValue)

terminal/src/main/scala/ammonite/terminal/Terminal.scala

@@ -36,7 +36,20 @@ object Terminal {
                filters: Filter,
                displayTransform: (Vector[Char], Int) => (fansi.Str, Int) = LineReader.noTransform)
                : Option[String] = {
+
+
+    val initialConfig = TTY.init()
+    try {
       new LineReader(ConsoleDim.width(), prompt, reader, writer, filters, displayTransform)
         .readChar(TermState(LazyList.continually(reader.read()), Vector.empty, 0, ""), 0)
+    }finally{
+
+      // Don't close these! Closing these closes stdin/stdout,
+      // which seems to kill the entire program
+
+      // reader.close()
+      // writer.close()
+      TTY.stty(initialConfig)
+    }
   }
 }