Combine commonly created scroll list menus into single menus identified by menu_num instead of their menu_file

sScrollListMenus is an array such that it will hold more menus in the future, such as groups.
fmenu_file still exists and will still exhibit its old behavior if used.
Fix Issue 870: Crouch toggle not reset when pressing "Fly" button, causes avatar to run/fly downhill.

Reimplements crouch toggle such that crouch is now tracked by the agent object
Fixes crouch being reset when restoring focus to the viewer window, as well.
Fix Issue 1344: Weird mesh distorted bug

Animations require consistent names for points like Avatar Center between viewers
To fix this, we now use Avatar Center instead of Root at the lower levels,
but this is okay, we translate Avatar Center into Root at UI level!
[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.
Version 1.8.5
Avoid potential buffer over-read in shader, overrun in application.
Revert "Limit avatar physics to 20-40 simulation steps per second to avoid wonky integration"

This reverts commit cde5b233530c3b43134039e8d8d5589b2daa28bf.
[RLVa] rlva strings floater!

Generalized toggle() visible() call pattern of rlv floaters to a template struct.
[RLVa] Version 1.4.9

Thanks to Trinity and, of course, her Kitty!