Merge branch 'jk/diff'

* jk/diff:
wt-status: remove extraneous newline from 'deleted:' output
git-status: document colorization config options
Teach runstatus about --untracked
git-commit.sh: convert run_status to a C builtin
Move color option parsing out of diff.c and into color.[ch]
diff: support custom callbacks for output

diff --cc .gitignore
Simple merge

diff --cc Makefile
Simple merge

diff --cc builtin.h
Simple merge

diff --cc diff.c
Simple merge

diff --cc git.c
Simple merge