Code Hints API is confusing about HTML escaping

[peterflynn]

The Code Hints extensibility API has some confusing semantics, mainly driven by the code in CodeHintList._buildListView():

• If you provide a match property, it assumes you're providing strings and not jQuery objects -- this is probably sensible, but it's not documented anywhere.
• If you provide strings, it assumes they're already HTML-escaped. This is undocumented, and confusing since we already support jQuery objects if you want to provide formatted output.
• If there is HTML markup or escaping in the string you provide, and you also provide match, it's possible for the match-text to match something in the HTML part of the string -- so the match-bolding logic will break the HTML code.

[peterflynn]

Marking low priority @RaymondLim, but nominating for 1.0 -- would be nice to clean up this API before then.

[pthiess]

Reviewed leave the 1.0 milestone. Seems like a small fix.