Bubbles can now be read and written with states

* This is by adding pointers to the bubbleTracker and the
  particleTracker to the State. This is not a good solution, but except
  writing a diff-based particle/bubble-tracker, this is the best
  solution.
* This invalidates previously generated binaries
* Closes #14 and #6
Merge branch 'master' of https://github.com/emiax/pink-fluid

Conflicts:
	src/pink-fluid-headless.cpp