minor typo fixes and reindenting.
moved `Board.swapBlocks` to `Swapper.swap`
now board doesn't shift its matrix representation every `moveBlocks`. it keeps only one matrix that grows indefinitely as the new rows appear.
minor typofix in `Board.newRow`.
now the swapper is initialized with it's board.
`Swapper` now handles its events completely.
lots of changes in board.js: `Board` now find matches in every update.
new `Block.explote` method.
making inactive blocks less opaque.
minor bugfix in `Swapper.swap` method.
a little bit of debug information in board.js with minor typofixes.
drying `Board.blocksGravity` using `Board.colGravity`.