Complete re-design of the astrotools in a ~2 weeks intensive session (add your proposals here):

• cosmic_rays.py --> particle_container.py
  • separate in container class and physical cosmic ray class
  • access physical keywords on demand (see issue #35 (closed))
  • add functionalities to immediately run basic analysis (2pt-auto, thrust, ...) on container class
• auger.py --> cosmic_rays.py or observed.py
  • auger related stuff in separate class AUGER, other stuff like simple power-law, broken power-law in separate functions
• merge simulations.py and auger.py ?