Priority based queue used in ChunkMeshUpdateManager.
Improving handling of shutdown (highest priority).
Make the passing of the camera position to the ChunkMeshUpdateManager robust and clear.
Add engine module as dependency for all modules
Merge pull request #1452 from msteiger/engine_mod_dep

Add engine module as dependency for all modules
Fix 2 typos.
Reordered methods in the WorldRendererLwjgl class. No functional changes. Related methods are now near each other. Accessors (getter, setter, etc) are now close together at the end of the file. This commit paves the way to split the class into two, one for rendering, the other for keeping renderable meshes up to date.
Merge changes from develop branch.
Moved much update functionality from WorldRendererLwjgl to new class RenderableWorldImpl.
Removed unnecessary variables from WorldRendererLwjgl. Logger moved to the RenderableWorldImpl class.
Moved chunk/mesh updating functionality out of WorldRendererLwjgl and into a new interface/class pair: RenderableWorld/Impl.
Removing WorldTime, and instead introducing the use of CelestialModel (obtained from CelestialSystem) for providing translation of GameTime (obtained from Time) to world time (days, etc).
Removing WorldTime, and instead introducing the use of CelestialModel (obtained from CelestialSystem) for providing translation of GameTime (obtained from Time) to world time (days, etc).