Initial Battery functionality.
More work on the Battery.

Signed-off-by: Decebaldecebal <rares_serban96@yahoo.com>
Derp in BaseElectricItem.
Battery Block bug fixes.
Battery almost finished.
Work on Battery GUI
Finished work on the Battery.Should be fully functional.
It has a 1 million initial storage capacity and 1000RF/t transfer rate.
It will charge the items in the 6 slot inventory and also use energy from them when exporting.
Max transfer rate is 10000RF/t (all sides combined)