I've taken the liberty of moving most of the math guts out of MediaWiki core into its own Math extension:
https://bugzilla.wikimedia.org/show_bug.cgi?id=14202 http://www.mediawiki.org/wiki/Special:Code/MediaWiki/85706
We meant to do this years ago -- I even got partway through it once but got held up on the horrid Special:Preferences system we had back in the day and never finished it. The modern Preferences class is a lot more flexible, and I was able to just grab the function that sets up that portion of the form and move it over. Yay!
There are a few cleanup bits still to do; I didn't want to dive into the message files just yet. There are some legacy interfaces on Language for getting the math option names, so that'll need a little more fixin' to remove those (the strings _should_ all be in the regular message area now) and then break the message files out.
People doing third-party packages of MediaWiki should take note: the texvc subprogram source will live in the extension now, not core, so build scripts for 'mediawiki-math' packages will need to be updated.
-- brion