And other minor code cleanup.

Without the flex/bison generated files, it's very hard to build the code
on Windows.

Contributors must simply remember to keep these files up-to-date if the .l
or .y files change.

Only tested with Visual C++ 2008.

Update ruby bindings for libconfig

- Fixed incorrect buffer switching.
- Fixed crash in scanctx_cleanup() when file list was empty.
- Fixed config_init() to properly set the default include function.
- Fixed memory leak when freeing file list.