Lab01: Allow vim, nano, etc. instead of just emacs.

Last semester, we allowed students to use editors (and give their keybindings on the test) other than Emacs. This branch changes the language of lab01 to reflect this.

If this is still course policy, the lab should probably reflect it (through this language or some other); if we will only be allowing Emacs for tests, then this change shouldn't be accepted.