updated to v0.2.1

Voltris updating to version 0.2.1!

As a new feature, there is now a downstacking algorithm alongside the already published perfect clear algorithm! This algorithm will take the next 5 pieces and try to find the best way to place the piece so that the board can be downstacked (tetris therm to talk about lowering down the board to avoid dying). This algorithm uses threads on the desktop version but since they are not available on browser you may experience some lag when using it there.

bugfixes: fixed a bug where the perfect clear algorithm  couldnt find some of the perfect clear involvings S/Z pieces