This add-on allows you to use <b></b> to bold text and <i></i> to make text italic. Simply add the tags then run the add-on and the text will change. It currently works on most questions (just added title text as well, not description yet). Please watch the video.

Important Note: You need to close and reopen before the update button will show up (after you install) also, apparently it works only for English characters not for UTF characters.