For some reason, early initialized tooltips without
a WDB cache, won't get attached properly. It seems
like they lose their owner when the WDB cache gets
ready. Running :SetOwner() again later when caches
are ready fixes that somehow.
* A memoizing method to cache and return hex colorstrings from rgb input.
* Refactor all occurences of adhoc rgb to hex string concatenation to use the new method
* Refactor chat module to use it
shagu