Bugfix in transverse damper. Infinit frequency damper was implemented.
Merge branch 'rfq' of http://github.com/like2000/PyHeadTail into kli
Merge branch 'rfq' of http://github.com/like2000/PyHeadTail into kli
Add lost particles in particles_2.
Some bugfixe in slicer e.g. betagamma in epsn_x, z_cut_head, floor, SI units for epsn.
Adds 'particle_indices_of_slice' method to slicer - indices are calculated by cython function.

  - Cython function 'find_particle_indices_per_slice' in cobra_functions/stats.pyx.
  - Higher performance (~ factor n_slices) than np.where().