Combined 4m/3m bits into an expanded bitfield.

Details:
- Combined the 4m/3m bits into an expanded bitfield, which will encode
  the packing "format" of the micro-panels. This will allow for more
  easily and compactly encoding additional formats.
- Other minor comment/whitespace updates to bli_type_defs.h.
- Updated bli_obj_macro_defs.h and bli_param_macro_defs.h to use the new
  format bitfield.
- Comment update to bli_kernel_post_macro_defs.h.
- Whitespace changes to bli_kernel_3m_macro_defs.h, _4m_macro_defs.h.
Merge branch 'master' of github.com:flame/blis
Merge branch 'master' of github.com:flame/blis