mint-arena: Add support for engine to notify CGame that glconfig changed

Called when r_fullscreen is changed if fast toggle is done instead of vid_restart.
Called when window is resized (r_allowResize 1 and drag window edge).
Preliminary custom class code
NOTE: cg_class? can be set from console at any time
Fixed using cg_class0-4 instead of cg_class1-5
Removed CVAR_ARCHIVE from cg_class* as it keeps ARCHIVE_ROM from working
Fixed G_SetClass not getting default loadout
Merge remote-tracking branch 'upstream/master'