Merge branch 'master' of git://github.com/psionides/git-subtree

* 'master' of git://github.com/psionides/git-subtree: improved rev_is_descendant_of_branch() function added temporary test dirs to gitignore added tests for recent changes fixed bug in commit message for split changed alias for --prefix from -p to -P fix for subtree split not finding proper base for new commits allow using --branch with existing branches if it makes sense added -m/--message option for setting merge commit message added -p alias for --prefix