Correct cobblestone texture

Fixes #953
Merge branch 'master' of git://github.com/overviewer/Minecraft-Overviewer
Fix more cobblestone textures

Also a comment typo and the base of a lever texture
Merge pull request #956 from duckman/patch-1

Fix more cobblestone textures
Merge branch 'master' of git://github.com/overviewer/Minecraft-Overviewer
1.6.2