DON'T MERGE feat(rxPageTitle): Strip HTML from page title

HOLD OFF ON MERGING FOR NOW

Closes #660
This is as close to a "standard" solution as there is, if you look around. HTML by definition can't be parsed with a regex.

I'm hesitant to move this to a general purpose filter because it's still dangerous. It'll execute arbitrary javascript, and we can't be sure that everything passed to it is causing from trusted sources.