Added 'use strict'; to all .js files
Removed baked in README in favor of github
Fixed problems with changing the working dir

It wasn't being created if it didn't exist already.
Re-indented. Whew!
Removed old-style Mutation detection

...replaced with a MutationObserver.
Renamed too-generic #ids in XUL

This fixes two warnings in the AMO validator:

    Overlay contains generically-named IDs
    Warning: An overlay is using a generically-named ID that could cause
    compatibility problems with other add-ons. Add-ons must namespace
    all IDs in the overlay, in the same way that JavaScript objects must
    be namespaced.
Removed nsIPrefBranch2 -> nsIPrefBranch

nsIPrefBranch2 is deprecated and as of FF 13 everything
is in nsIPrefBranch, so use this.

This was a compatability warning in the AMO validations.