[RLVa] f9f8dbe23ec3 ported

- internal : reviewed @startim for CHUI (SL-3.5)
    -> fixed : "Start Conference Chat" on a selection of multiple calling cards opens an IM session
    -> fixed : actions that would result in an IM window opening shouldn't be blocked if the session is already open
    -> added : RlvActions class to mimick LLAvatarActions and lowering the rlvhandler.h include dependency
[RLVa] Disallow inventory floaters when inventory restricted.

Formatting eases the diff with rlva upstream
[RLVa] b15fdd026026 ported

- internal : reviewed @recvim and @sendim for CHUI (SL-3.5)

Singu changes:
- Updated busy to be referred to as do_not_disturb in llviewermessage.cpp
- Don't send autoresponse if we can't send an IM by rlva
- Updated checks for from name being system to be to_id and from_id null checks.
- Minor compile fix in rlvui.cpp for last commit.
[RLVa] Modernizations

License updates, comment updates, settings cleanup, macros cleanup, dead code removal, etc.
[RLVa] rlvfloaterbehaviour.* -> rlvfloaters.*
[RLVa] Removal of z offset restrictions
[RLVa] Forced TPRequest response is now supported!
[RLVa] gRlvHandler.canStand --> RlvActions::canStand
[RLVa] "blocked_wireframe"? Seems half baked, but it compiles.
[RLVa] Missed sections of canStand update in that last commit.
[RLVa] Miscellaneous other touches to rlva code
[RLVa] rlva_strings update.

rlva strings floater coming soon!

I highly doubt the translations work anymore
If they still can be translated, I leave it up to translators to decide if they should be
Contact me if you need translation code improved here.