Fixed #69 - Configure ANTLR dialog has no effect

It looks like the problem lies in an inconsistent representation of paths - config dialog uses `VirtualFile.getPath` (which seems to output absolute paths), and the action itself `VirtualFile.getPresentablePath` (relative paths here). For the sake of consistency, I've replaced both with `getCanonicalPath` which, by the name of it, should be the most reliable of the three.

Additionally, it looked like package name option wasn't handled at all - I've added the code.

Also, I couldn't help myself from fixing some whitespace issues here and there. I hope you don't mind.

The deadlock error still prevails, unfortunately - it looks like it's an unrelated issue to the one at hand. My knowledge of IntelliJ SDK is too limited to tackle it, sadly.