Tweaked textures to be more vibrant and simillar to original Minecraft

I've tweaked textures to be more contrast and better-looking with fog.
Sand texture is now more vibrant and distinguishable from far. Sky
color and textures are more realistic and similar to original Minecraft.
Added function to fly up or down using space and shift key (in flying mode)

In flying mode, I added keys to fly up (space key) or fly down (shift
key) along y axis. I also fixed wrong inital rotation.
Merge remote-tracking branch 'avelanarius/master'