Merge branch 'js/diff-color-words'

Merge branch 'js/diff-color-words'

* js/diff-color-words:
  Change the spelling of "wordregex".
  color-words: Support diff.wordregex config option
  color-words: make regex configurable via attributes
  color-words: expand docs with precise semantics
  color-words: enable REG_NEWLINE to help user
  color-words: take an optional regular expression describing words
  color-words: change algorithm to allow for 0-character word boundaries
  color-words: refactor word splitting and use ALLOC_GROW()
  Add color_fwrite_lines(), a function coloring each line individually