Improved Entity interface.

* Removed getPosition, getX, getY, getZ in favor of getLocation
* Removed getVectorRotation in favor of getRotation
* Removed EulerDirection in favor of Vector3f
* Removed interact methods as they are meant for Players
* Removed eject in favor of setPassenger
* Removed dismount in favor of setVehicle
* Renamed getRiding in favor of getVehicle
* Renamed getRidden in favor of getPassenger
* Renamed teleport to setLocation
* Renamed isDead to isRemoved
* Updated javadocs
Add PotionEffectBuilder.
Remove flags from setLocation, add getBaseVehicle
Rename isValid -> isLoaded
Merge pull request #290 from SpongePowered/feature/entities

Improved Entity interface.
Add API for force-loading chunks
Added BlockBreakEvent and ExpEvent.
Renamed ExpEvent to ExperienceEvent
Added support for BlockBreak, BlockPlace, BlockInteract events.

* Added BlockPlaceEvent
* Added BlockInteractEvent
* Added EntityBreakBlockEvent
* Added EntityInteractBlockEvent
* Added EntityInteractEntityEvent
* Added EntityPlaceBlockEvent
* Added PlayerPlaceBlockEvent
* Added PlayerBreakBlockEvent
* Added PlayerChangeBlockEvent
* Added PlayerInteractBlockEvent
* Added PlayerInteractEntityEvent
Merge pull request #303 from SpongePowered/feature/events

Added support for BlockBreak, BlockPlace, BlockInteract events.
Added support to handle persistent living entities.
Updated Entity setRotation and getRotation to use Vector2f as entities

only use yaw and pitch but not roll.
Move Contribution Guidelines to SpongeDocs
Update Checkstyle and enable settings
Fix some of the checkstyle warnings
Move plugin workspace setup to SpongeDocs
The concept of environments.
Merge pull request #311 from CraftStone/master

The concept of environments.
Add getter for entity class in EntityType
Expand Block/Item interfaces