Remove topics from messages and replace with Joomla tags.

[genu]

Related to #118

Absorb the JBS topic system into the new Joomla Tags mechanism.

[bcordis]

This may be an option to convert them into tags without a problem. Thin linking the tags to the old messages. This must be done as we will soon be moving away from the topics system.

[tomfuller2]

Should we tackle this now? How hard/easy would it be? Perhaps this is for after 10.x? Or if not hard, it would simplify our code and we could get rid of the current topics admin and migrate Proclaim topics to Joomla tags.