Alpha for the beam select menu. Default bind is Q.

Two cvars added for it:
- metroid_cl_showallbeams, which adjusts the menu to have a spoke for each beam.
- metroid_cl_nospselectfreeze, which disables the "freeze game in SP when selecting" behaviour.

Note that since I don't have greyed-out or translatable icons for the beams,
right now beams you can't use simply aren't displayed. This should probably be rectified.