message: Made a note of the coordinate system change in the changelog.
diff: * First off, there will be some switches in process: We're going to make the master branch STABLE, tracking the latest release,
  and create a devel branch that new work will be pushed to. That way people don't check out master and get some WIP stuff.
  + * The coordinate system moved from origin-at-center, x-increasing-up to origin-at-top-left, x-increasing-down
  * Updated all dependencies to newer versions
  * Refactored EventHandler interface, again
  * Altered timestep functions to be nicer and made examples use them consistently
  