Variable navigation

[brunowonka]

Implement reference resolution for variables, so that ctrl+click navigates to the point where that variable was first introduced.

Question remains whether we navigate to first declaration in block or first use in rule, like:

template("foo") {
   group(invoker.name) {
      #...
   }
}

foo("bar") {
   # Should name reference the usage in the foo template declaration above?
   name = "a"
}