Improvements to chat message formatting

[Timwi]

• Do all of the formatting in one pass, so you don’t get situations where a glossary term occurs inside of a URL and messes up the generated HTML.
• Allow bare URLs as well as URLs enclosed in angle brackets (to allow more special characters, which the browser automatically UTF-8 escapes).
• System is now more flexibly able to accommodate future things that may want to be HTMLified/linkified/adorned/etc.
• Since this is now all handled in one place, call that place chatformat.js instead of glossary.js