Setting up compiler support and several related additions to util/io

* Added the top-level interface project for communicating across scala versions within a jvm.
 * Added plugin project containing analysis compiler plugin
 * Added component compiler to build xsbt components against required version of Scala on the fly
 * Added interface to compiler that runs in the same version of Scala
 * Added frontend that compiles against a given version of Scala with or without analysis.

interface/src/main/java/xsbti/F0.java

@@ -0,0 +1,9 @@
+/* sbt -- Simple Build Tool
+ * Copyright 2009  Mark Harrah
+ */
+package xsbti;
+
+public interface F0<T>
+{
+	public T apply();
+}