Add magit-push-head command
Update Magit and git-modes setup

Magit now contains git-commit-mode.el, git-rebase-model.el, and
with-editor.el from the git-modes repo.

Magit commit 6e601926278a833baed7a9f44f7f6a360be203da
snakemake-compile-project-file-at-point: Add jobs flag
Add command snakemake-compile-project-rule
project-filename-at-point: Return nil if no file
snakemake-compile-project-file: Add file prompt

Fall back to file prompt when there is no file at point.