Added combos.

-Blockgrid changes the combo boolean to true when a row is cleared. It
also doubles the multiplier.
-Ingame has a counter to turn combos off and to change the multiplier
back.
-There was a merge conflict, so I think my files are going to show
everything as committed. The following lines were changed:
blockgrid: 100 -103
ingame: 36, 44-47, 124, 142-144, 170-176