Power class now has ability timer that tracks cooldown.

Player still responsible for the ability itself but
whether the ability can be used is tracked by Power.

Also added a duration on the power that prevents collection
of more power while it's running. This may be changed later,
in which case the Power timer needs to be refactored to
test for curValue == 0.
Temporary shields added on green power usage.

Can no longer switch to green.
Only one power at a time can be active now.
Blue speed-down and speed-up implemented on blue activate.

New sound added too.
Crystal pickups now can be randomly assigned a color on spawn.
Neutral color added for Pigment when not using colors.
Colors now change background and Laser Upgrade added.
Demo build with more shields and laser at store.