[Azoth] Use trimmed() instead of simplifed() in tooltip str.

Speeds tooltip generation considerably, cutting off around 300 ms on
joining to irc.freenode.net#haskell with ~1300 participants on my machine.
[Azoth] Core::MakeTooltipString() should be non-const.

In preparation for avatar cache.
[Azoth] Avatar cache for tooltips.

Cuts off around 4 seconds joining time to #haskell on my machine.
[Azoth Acetamide] CreateParticipantEntry() announce flag.

CreateParticipantEntry() now can avoid announcing the entry right away.
[Azoth Acetamide] Make join message after status has been set.
[Azoth Acetamide] Announce the entry after its state is set.

Otherwise stuff is slow on tooltip rebuilding etc.