Merge branch 'ak/pretty-decorate-more'

"git log --format" has been taught the %(decorate) placeholder.

* ak/pretty-decorate-more:
  decorate: use commit color for HEAD arrow
  pretty: add pointer and tag options to %(decorate)
  pretty: add %(decorate[:<options>]) format
  decorate: color each token separately
  decorate: avoid some unnecessary color overhead
  decorate: refactor format_decorations()
  pretty-formats: enclose options in angle brackets
  pretty-formats: define "literal formatting code"