v0.5 Shake added!

Additions:

1. Play Screen:
   1. Added a new shake mechanic
      1. Ui will display a bar that fills under the item store
      2. every merge will contribute to the bar-filling
         1. some items give more to the bar
      3. once the bar is filled it will light up blue
   2. Controls
      1. middle click to activate shake
      2. press Y or triangle to shake