Make CParserBase.__init__()'s interface more compatible to pycparser's CParser.__init__()

[manueljacob]

This makes it possible to almost use pycparserext as a drop-in replacement for pycparser. E.g. it's now possible to pass additional arguments which are passed through to pycparser's CParser.__init__().

This changes behavior slightly:

• By default, lex and yacc are now run with optimizations. This can be changed back by passing the right arguments (see pycparser's documentation).
• We don't pass 'write_tables=False' to yacc anymore. Unfortunately, pycparser currently has no option to disable it. This is why I added 'lextab.py' and 'yacctab.py' to .gitignore.

[inducer]

OK, fair enough. Let's give this a shot. Thanks for your contribution!