Painting Mode

There are three painting modes:


 * 1) Normal - Paint with your brush normally.  All existing blocks are overwritten.
 * 2) Paint - Paint only the block type (i.e. texture).  The block shape and size remains unchanged.  Empty blocks are unaffected.
 * 3) Fill - Paint with your brush normally, but only empty blocks are filled in.  Tiles that already have a block are unaffected.