Added air resistance
Added levels with increasing speed and obstacle count.
Added level.js
Fixed jettery camera.
Added slowing and speeding objects to the map
Merge branch 'Increasing_fall_speed_(Air_resistance)'

* Increasing_fall_speed_(Air_resistance):
  Added slowing and speeding objects to the map
  Fixed jettery camera.
  Added level.js
  Added levels with increasing speed and obstacle count.
  Added air resistance