Added support for creating all types of breakable blocks.
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.
Merge from upstream.

Merge branch 'master' into blocks
keys 1 - 0, not 0 - 9
How to play instructions in README

Key bindings and mouse actions
Merge pull request #18 from RichVel/master

"How to play" instructions in README
Update README.md