Added optional MainClass feature (load MainClass to Scene and check for overwriting methods)

* Added missing .classpath file for Eclipse support
* Added m_overwrittenRefs property to DfsInfo.java (method body parsing in OpenCLScene)
* Added command line option "-mainclass" in RootbeerClassLoader.java
* Moved Pair class from rootbeer to soot-rb
* Fixed quoting issue in SootMethod.java
  * SootMethod does quoting, HierarchySootMethod and MethodSignatureUtil do not
* Fixes in RootbeerClassLoader
  * doDfsForRootbeer: check for [] in class names
  * doDfsForRootbeer: do not add root virtual_method to queue (doDfsForRootbeer was done twice for root virtual_method)