Add basic support for mouse input, left-click -> break / right-click -> place.  Slightly bugged so that the view cannot be adjusted while breaking/placing.
Make Block names capital, reversed Block class names (GrassBlock -> BlockGrass) and moved blocks to separate package
BlockDirt now generates and is collected when mined.  It can also be placed like other blocks
Merge pull request #2 from warriordog/master

Update block_changes branch