Changes to llviewermenu.cpp are better viewed without space changes
^Put together both RLVa Embedded and RLVa Main menus while building Advanced menu, labeling them RLVa; once the advanced menu is built and added to MenuBar, rlvMenuToggleVisible() is called.
Added onChangedMenuLevel() to rlvcommon.cpp
Added rlvMenuToggleVisible(), tweaked to only perform necessary operations for now, other parts left commented out for future use.
Removed menu visibility handling from RlvHandler::setEnabled()
NOTE: RLVa has only been updated in pertinent areas, from what I can tell we are a bit behind in other places, too.
Most in particular llevents.h, which comes along with
the demand that the old events in llevent.h are put
in a namespace LLOldEvents. Made all changes necessary
to compile the rest of the code again (without changing
the actual code: it's still using the old events).
This patch also removes LLStopWhenHandled and LLStandardSignal
from indra/llui/llnotifications.h because those are
moved to llevents.h. That seems to be the only change
to indra/llui/llnotifications.h that isn't floater related,
so I left the rest of that file alone.
