* Slightly optimized the command manager
* Added a "/veinminer toggle" subcommand to toggle whether VeinMiner is active or not
* Added a permission node for the new "/veinminer toggle" sub-command - "veinminer.toggle", default to all players
* API: Added methods for the new toggle functionality under the VeinMinerManager class
* API: Added a PlayerVeinMineEvent#getAffectedBlock() method to get which block was modified
* Fixed a few memory leaks with clearing localized veinminable block data