Make Rule class composable

Add ValueClassInstantiationPlugin
Add link to Jason Zaugg -- author of plugin
Move success/failure to Rule object
Move scalaVersion to project/build.scala

Update scalaVersion to 2.10.2
Configure prompt to show current project
Make `Rule` constructor private

Rename `isMatched` to `matched`
Remove debugger-helper `opTree.show` from OpTree hierarchy. Should use `toString` instead
Remove redundant parentheses in `fromTree`
Rename `OpRule` to `RuleCall`