Better viewed without space changes
Pretty much add support for sending LLAvatarName and std::string to become a name via the system...
Also a bit of a revert for llcallingcard.cpp in this regard, just allow it to use a callback along with the new support,
but still handle the actual name switching in LLAvatarNameCache.
Fixes a problem I was having with "[NAME] is Online" notifications appearing early on, only.