This removes the need to explicitly pass thru min_indent when using the parser combinators.
My ultimate goal here is to evolve the current parser closer toward a purely combinator-based parser,
at which point we can more easily transition smoothly to a formal(ish) grammar, or expand the meanings of combinators
to include things like:
* Incremental (re)parsing
* Unified parsing and formatting code
* Better error recovery
* Using the main parser directly for syntax highlighting
This fixed a bug where bindgen was providing cwd() for src_dir,
but actually the src_dir should have been based on the filename.
This prevents that problem from happening in the future!
