Changed use of `git stash` from `save` to `create`

By using the `create` option instead of `save`, we don't have to pop the
stash afterwards, or even drop it, we just have to tag the reference git
gives us.
Merge branch 'master' into dev
Changed license to one that makes more sense for code

Not that the Creative Commons licenses can't be used for code, (maybe
they can? I don't know) but GPL makes more sense for code.
Releasing everything under GNU GPL v2.0
Updated version to 0.5.1
Merge branch 'dev'

Release v0.5.1