Add togglemenu command.
Make UI_CVAR_CREATE use VM specific code

Makes cvar be flagged as VM created and unset ROM if ARCHIVE is set.
Fix MSG_ReadDeltaKey setting bit 1<<bits often

MSG_ReadDeltaKey would often set 1<<bits, it should never be set. It exceeds the size of what was being read.
Worked okay for weapons/forward/right/up as they stored as chars (value would wrap around to correct value, lucky).
Angles had the wrong value, not sure if it was causing issues.
Remove MSG_WriteDeltaUsercmd and MSG_ReadDeltaUsercmd
Fix resolving IPv6 favorites in Team Arena UI
5717 - Gamecode can open file "" for reading
On Windows, add \r\n to each line of the console dump.
5097 - Menu corrupted on start (on IRIX)

(Unvanquished/dsalt: GL_ACCUM_BUFFER_BIT removed from the glClear() calls.
We don't use any accumulation buffers.)