Add piece bounce to the drop animation

Fixes #26
Split up drawing the drop_x and drawing the drop preview
Wait to draw the drop_x for a bit after dropping a piece

This prevents the drop_x from obscuring the drop animation.
On new game, change the existing animations to not bounce
Complete bounce animations when starting a new game

Currently drop animations in their bounce phase are cut off.
Undo accidentally committed code from the last commit

From 9b3b0c60dc96cfe341f84fbf783605b38ccc6230
Fix bug in View.drop_all_pieces_off_of_board_from_current_location ignoring the x when matching existing animations
Restore the animation speed