Everything updates... now with less duplicate code
Average input tracking added to Charging Bench tile entity
Added tile entity support for some item charging stats to charging bench
Relocated energy > 0 check to avoid possible stats bugginess with an empty bench
base tier is for charging, not power tier

Probably didn't affect behavior since a check was already performed, but
should be consistent anyway.
Container code for new CB GUI features
Finished GUI enhancements for Charging Bench