Merge branch 'jc/mktree' into sb/opt-filename

* jc/mktree: mktree: validate entry type in input mktree --batch: build more than one tree object mktree --missing: updated usage message and man page mktree --missing: allow missing objects t1010: add mktree test mktree: do not barf on a submodule commit builtin-mktree.c: use a helper function to handle one line of input mktree: use parse-options build-in git-mktree