Balance tweaks including treadmill speeds, and item effectiveness.

Magnets now actually only pull at 6m instead of 10m.
Powers require 40 crystals to fill instead of 30.
Acceleration of treadmill was increased.
Had a change of heart on Power limits. Went down to 35 and 30 for upgrades.
Merge branch 'balance_tweaks'

Conflicts:
	Assets/Scripts/Treadmill.cs