Added a new block item ItemStone that will represent any block that uses stone names,

that way we only need 1 class instead of 6, or more. Also refactored
grass, dirt, clay and sand to use one class. Removed unneeded item and
block classes. All blocks are being added correctly to the creative tab,
with correct tool tips, even the middle mouse button works on these
blocks now and they are being localized correctly. Also changing
"addToCreative" to false in the "getSubBlocks" method will prevent the
blocks to be added to the creative tab.