EXP bars need redoing

[wildweasel486]

Because the number of kills required for a weapon level is now user-adjustable, the way I wound up doing that means that the DrawBars on the HUD no longer actually reflect the progress towards an upgrade, and remain blank for the entirety of the game.

I think this may need to be fixed with ACS; likely, hash out a percentage number instead, and assign that to the drawbar instead.

[wildweasel486]

Thanks to a kind submission/idea by PillowBlaster, two-year-old issue can now be safely closed.