Move the command API to .util.commands.
Add a sevice manager interface and Owner interface.
Add preliminary permission service.
Add preliminary command dispatcher service.
Update Block's ID call and update its Javadocs.
Add Identifiable interface and make Entity use it.
Add Extent as a super interface for World.
Add missing @Override in BaseEvent.
Add causes for events.
Update Javadocs for EntityEvent.
Simplify Event.
Make EntityEvent use a list of affected entities.
Add EntitySpawnEvent and AbstractEventEntity.
Remove BaseEvent.
Rectify incorrect grammar

Affects the JavaDoc for EulerDirection
Merge pull request #188 from DziNeIT/patch-1

Rectify incorrect grammar
PluginContainer.getID() -> PluginContainer.getId().
Add GameEvent, child of Event, parent of game events.
Add VanillaGameMode enum and GameMode, GameModeEvent, PlayerGameModeChangeEvent interfaces