Adding properties to expose useful information to derived classes, also ...

...changed 'file' (a keyword) to 'rcsfile' in the ctor and made self._filename a tuple

I apologize on behalf of my editor which tends to strip trailing whitespace.

The exposed properties allow me to derive a class and do meaningful stuff in that derived class, since all relevant parsing data is now available.

This includes the fixes suggested in Issue #1 of the upstream repo.

As a side-note: your code ran fine with `pyparsing` 2.0.3.