Minor style fixes.
Fixed support for 1.8's string-based item ids.
Convert data types during server.properties migration (fixes #392).
Added player visibility API (closes #121).

Players are hidden fron another player's tab list and entity updates.
Also renamed other canSee methods to canSeeChunk and canSeeEntity.
A basic start on physics, including bounding box search.
Implement some basic entities.
Implemented the Painting entity, as well as NBT storage and retrieval
Implement remaining LivingEntities
Fix code style according to checkstyle.xml. Add remaining required class checks for spawning all other entities.
Clean up spawn method to use entity class registry.
Simplify GlowPainting and abstract as-necessary methods to GlowHanging.
Fix GlowPlayer Imports.