TMP: fixes for git-1.7
TEST: test editing
REFACTOR: do not return unknown commits from read_todo
TEST FIXUP: really test editing todo
TEST FIXUP: use existing editor
Merge compat_git17
COMMIT PLAN: described what I want to do
COMMITS IMPL: change to use the proposed data strcture
TEST: add testing with unlnown commit
TEST FIXUP: add the testing editor
FIXUP: properly print the subject
DOC: marked done