Merge branch 'nd/negative-pathspec'

Introduce "negative pathspec" magic, to allow "git log -- . ':!dir'" to
tell us "I am interested in everything but 'dir' directory".

* nd/negative-pathspec:
  pathspec.c: support adding prefix magic to a pathspec with mnemonic magic
  Support pathspec magic :(exclude) and its short form :!
  glossary-content.txt: rephrase magic signature part

diff --cc pathspec.c
Simple merge