Switch from 2*sigma to h_cut criterion in generator.
Speed up convergence in generator.
Move longitudinal trackers to simple trackers.
Merge branch 'rfq' of http://github.com/like2000/PyHeadTail into kli
Fix wake_strength[0] entry in class WakeTable.
Remove reference in slicer staistics.
minor compatibility correction
Merge branch 'kli' of https://github.com/like2000/PyHEADTAIL into kli
Separate RFBucket and RFSystems.
Replace n_particles by particlenumber (alias QM operator).
Fixes bug in wake kicks. Kick only particles within z cuts.

 - does not work with particles.slicer module.
 - use particles.slicer_2.
Comment 'import pylab as plt'.
Removes boundschecks for cython functions.
Comment 'import pylab as plt'.
Initialize attribute n_macroparticles_lost in constructor.
Adds cythonized slicer stats. Removes boundschecks.
Do slicing without sorting but with np.floor.

 - For performance reasons.
Temporary longitudinal tracker for linear tracking.