Merge branch 'jk/shortlog'

Merge branch 'jk/shortlog'

"git shortlog" used to accumulate various pieces of information
regardless of what was asked to be shown in the final output.  It
has been optimized by noticing what need not to be collected
(e.g. there is no need to collect the log messages when showing
only the number of changes).

* jk/shortlog:
  shortlog: don't warn on empty author
  shortlog: optimize out useless string list
  shortlog: optimize out useless "<none>" normalization
  shortlog: optimize "--summary" mode
  shortlog: replace hand-parsing of author with pretty-printer
  shortlog: use strbufs to read from stdin
  shortlog: match both "Author:" and "author" on stdin