Fixed up .gitignore to ignore more useless stuff.
Renamed UnitTests to UnitTest so maven will run them automatically.
Changed scheduledAdds and scheduledRemoves to use List interface instead of LinkedList in the definition.
Entity.getComponents() returns components regardless of being attached to world.
Entity.hasComponent(Class) and Entity.getComponent(Class) now work without entity being added to world.
Changed Entity methods dealing with component ids to throw IllegalStateException instead of RuntimeException when entity not added to world.
Entity.getComponent(int) now returns Component instead of Object.
Removed unused import from Entity.
Entity.hasComponent(Class) and Entity.getComponent(Class) should match exact classes only.
Fixed NPE in EntityWorld.getScheduledAdds/Removes
Added some basic entity tests.