More precisely locate the name bindings of a variable

Previously we were using the entire CompilationUnit. While this works,
it is too coarse-grained. We should start looking for bindings at the
smallest encompassing unit, i.e, a MethodDeclaration for our case.

See #33.
Refactor to remove unused method parameter

Discovered as part of integrating our PDG into the extract closure
refactoring.

See #37.
First draft at getting our PDG into the Extract Closure workflow

Mostly consists of exporting/importing packages from various plug-ins.

One important fact to realize is that to grab the IDocument we need
to run in the UI Thread. Hence, we use

		Display.getDefault().syncExec(new Runnable() {

See #37.