Smooth Movement Patch

Added interpolation to make movements smooth even on low fps (prevents stutter like movements). This is applied to player, enemies and things that are pushed. Now even on 30 fps it is possible to finish within time limits.

Detail: Due to how the movement of the game is (move one tile, then calculate next move) it stuttered every full step (visible on fps lower than 60). This was fixed with adding interpolation to movement, so extra movements pass on to the next step so that no jitter or stutter occurs. Also this speeds up movement by getting back lost displacement due to the pause and snapping that was removed.

Multiple levels were tested, and behaviour of objects were tested at least once. Some key levels were tested, along with a few others. Hopefully no levels break, not unexpected behaviours introduced (Prayge). Game should run nearly the same on 60fps though.