Better formatting of update-dot-files output
Preserve $PROMPT_LEVEL in subshells
Add `git merge-to` command
Add `git with` alias

This checks out a branch and starts a subshell. When you are done, close
the subshell, and your original branch is checked out again for you.

Usage example:

	$ # on develop branch
	$ git add .
	$ git commit -m "Done developing, time to go live"
	$ git with master
	Switched to branch master
	$ git merge develop
	$ git push origin
	$ exit
	Switched to branch develop
	$ # Contiune developing, you are automatically back on develop!

Alternatively, for hot fixes

	$ # Working on develop...
	$ # Oh no, the live site crashed! Time to hotfix
	$ git stash
	$ git with -b hotfix-crash master
	Switched to new branch hotfix-crash
	$ # Fix the stuff...
	$ git commit -m "Fixed it!"
	$ git merge-to master --no-ff
	$ git merge-to develop --no-ff
	$ git push origin master develop
	$ exit
	Switched to branch develop
	$ git stash pop
Made update-dot-files awesome at printing