Implementation of Psi references and search

The previous mechanism was not correct in the sense that a macro was
not referenced by its method. @Macro("Foo#bar") will contribute two
references now. One for "Foo" and one for its method "bar".

The reference search is also correct in the sense that we don't use
IntelliJ's default scope (module with dependencies) but build our own.
The macro inside a web project might as well be referenced from generic
code which doesn't share a dependency in IntelliJ's cosmos.
Auto-completion for macro class reference and narrow method search

The method search may simply search for "#method" which should yield
less results than "method".

The macro class was not found before since defrac.compiler.macro.Macro
is not part of the macro search scope.
Merge pull request #9 from joa/master

Implementation of Psi references and search