Merge branch 'bw/diff-opt-impl-to-bitfields'

Merge branch 'bw/diff-opt-impl-to-bitfields'

A single-word "unsigned flags" in the diff options is being split
into a structure with many bitfields.

* bw/diff-opt-impl-to-bitfields:
  diff: make struct diff_flags members lowercase
  diff: remove DIFF_OPT_CLR macro
  diff: remove DIFF_OPT_SET macro
  diff: remove DIFF_OPT_TST macro
  diff: remove touched flags
  diff: add flag to indicate textconv was set via cmdline
  diff: convert flags to be stored in bitfields
  add, reset: use DIFF_OPT_SET macro to set a diff flag