Proper Flux Modifiers + Blockbreak-Bug fix

Flux Modifier can be added in any slot now, not only 0 and 1.
Flux Modifier uses battery properties, including charging rates.
Flux modifiedtTools will try to fully charge themselves from items in the hotbar when mining something. This prevents the blockbreak-process-resets-on-metadata-change problem. Wasn't ported from 1.6.4.
Flux modified tools. can be upgraded with better batteries.
Contains backward compatibility to old values in case a tool doesn't have the new tags yet.