Made minor changes in the way classes are inherited to pave the way for easy-to-extend executable messages.
Added a few more messages and Executable Message prototypes.
Implemented ExecutableLoginRequest and necessary changes.
Finished implementing player login.
Added WorldSqlHandler class
Properly synchronized login.
Added IllegalArgumentException to World.addObject()
Fixed logger typo
Renamed ClientTest to ServerTest, as it more appropriately describes the tests being run.
Added login and logout functionality to WorldSQLHandler, including automatic saving of coordinates.  Closes #39.
Added ActorInfoClass, moved Vector2D and Round to jgcf.
Added ActorInvisibleMessage, ExecutableActorInvisibleMessage prototype.
Package restructuring
Added caching for MoveDirection.
Implemented ExecutableStateChangeRequest.  Closes #37.
Merge pull request #44 from floralvikings/executable-messages

Executable messages