* minor updates to documentation
* C-level:
- simplify and speedup `extend_unicode01()`
- customize `resize_lite()` - avoid unused code
- use `PyTypeObject` for bitarray type object in `_util.c` to
be consistent with `_bitarray.c`
- add and improve comments to implementation of sparse bitarray
compression
- simplify `sc_count()`
OBS-URL: https://build.opensuse.org/package/show/devel:languages:python/python-bitarray?expand=0&rev=70
