Added textures for standard blocks.
* red and black tower stone are now new blocks
* cobblestone and brick are "neutral" blocks
Adds some more fixes and tweaks in the World Renderer class.

* Fixes that "pendingChunks" was never reset to false and thus caused the chunksInProximity list to be recreated each frame
* Removes the no longer necessary chunk mesh disposal while adding chunks to the render queues
* Adds that chunk meshes get removed from the VRAM via dispose() when leaving the chunksInProximity list
* Renamed some enums for consistency
Fixes broken FBO error handling and removes exception if something goes wrong so the application does not exit instantly.

* Adds missing "GL_FRAMEBUFFER_UNSUPPORTED_EXT" error case
Adds flag to hide/show the hud to the config file as a debug flag. Also fixes that hiding the HUD or first person view elements via the H key could become inconsistent (first person view is visible while the hud is not and the other way around - and there was no way to fix it without touching the config file).
Added crops and dice textures.
* crop textures suffice for a 3 to 5 stages growth process
* classic white, red and black dice texture
- removed placeholder texture
* removed duplicate entry in plant.json (engine)
Merge pull request #595 from skaldarnar/lightAndShadow

L&S content (art assets)