Separate monolingual and multilingual code as files, not branches

[jtmorgan]

I just checked in an update to the enWiki branch, with the version of the code which is currently at https://test.wikipedia.org/wiki/MediaWiki:Gadget-formWizard.js

But we really have two separate codebases now: one that works with monolingual wikis and one that works with multilingual wikis. These should be separated out into to separate .js files, I think. What do you think?