* Add Device3D class which will contain IrrlichtDevice interface
move getSupportedVideoDrivers to Device3D
Add Device3D singleton & use it in various places
Rename Device3D to Rendering engine & add helper functions to various device pointers
More singleton work
RenderingEngine owns draw_load_screen
move draw functions to RenderingEngine
Reduce IrrlichtDevice exposure and guienvironment
RenderingEngine: Expose get_timer_time() to remove device from guiEngine
Make irrlichtdevice & scene manager less exposed
* Code style fixes
* Move porting::getVideoDriverName, getVideoDriverFriendlyName, getDisplayDensity, getDisplaySize to RenderingEngine
Fix XORG_USED macro -> RenderingEngine + create_engine_device from RenderingEngine constructor directly
* enum paralax => enum parallax
Pass drawtype and material type to shaders.
Move shaders generation to startup only.
Allow assign shaders per tile.
Initial code to support water surface shader.