Merge branch 'mg/gpg-richer-status'

The GPG verification status shown in "%G?" pretty format specifier
was not rich enough to differentiate a signature made by an expired
key, a signature made by a revoked key, etc.  New output letters
have been assigned to express them.

* mg/gpg-richer-status:
gpg-interface: use more status letters

diff --cc Documentation/pretty-formats.txt
Simple merge

diff --cc pretty.c
Simple merge