[ffigen] Update headers config. (#60)

Closes #52 
- Updated headers config to have sub-fields `entry-points` and `include-directives`, removed `header-filter` config.
- Globs are supported by both subkeys.
- Updated tests, examples, readme, changelog.
30 files changed
tree: ecd76b6ee5a0a6586ce797d02e86ef62ea89a067
  1. pkgs/