[PATCH 0/14] counting trailers with shortlogs

I happened to be reading an old discussion on trailers a few weeks ago, and the idea was mentioned of providing access to commit trailers in a more structured way from traversal commands. E.g., we could presumably have a log pretty-format for showing "Signed-off-by", like "%(trailer:signed-off-by)" or something. But that opens up a lot of questions, like the exact formatting, whether we would allow wildcards ("*-by:"), and if so how that affects formatting.

So I took the cowards way out and implemented trailer support for git-shortlog, which seemed much simpler. I'll admit I haven't used it for anything so far beyond a few "fun" queries, but it does provide some infrastructure we could use later for git-log.

And things being what they are, I ended up with a few cleanups and optimizations along the way. After this series, a regular "shortlog -ns" is about 10% faster.

  [01/14]: move string functions out of git-compat-util
  [02/14]: log: refactor add_header to drop some magic numbers
  [03/14]: strutil: add skip_prefix_case
  [04/14]: shortlog: use skip_prefix_icase to parse "Author" lines
  [05/14]: shortlog: use strbufs to read from stdin
  [06/14]: shortlog: replace hand-parsing of author with pretty-printer
  [07/14]: shortlog: optimize "--summary" mode
  [08/14]: shortlog: optimize out useless "<none>" normalization
  [09/14]: shortlog: optimize out useless string list
  [10/14]: shortlog: change "author" variables to "ident"
  [11/14]: shortlog: allow grouping by committer ident
  [12/14]: trailer: factor out config reading
  [13/14]: trailer: add interface for parsing commit trailers
  [14/14]: shortlog: match commit trailers with --ident

-Peff