Moves RFQ implementation (not completed yet) from detuners.py to folder rfq.
Merge branch 'kli' of https://github.com/like2000/PyHEADTAIL into rfq

Conflicts:
	trackers/detuners.py
Cleans rfq branch.
Removes particles/beams.py and particles/bunch.py (see not_used_bunch.py).
Adapts indentation.
Renames detuners: Sextupole -> Chromaticity  /  Octupole -> AmplitudeDetuning.
Finishes first implementation of RFQ. Ready for testing.
Generate segment maps in transverse tracker instead of detuner collection classes.

 - allows cleaning of collection classes (reduce number of attributes)
Merge branch 'kli' of https://github.com/like2000/PyHEADTAIL into rfq
Cosmetic changes and comments.
Merge branch 'kli' of https://github.com/like2000/PyHEADTAIL into rfq
Add changes made to property 'gamma' by oeftiger.
Replace slice and bunch statistics attributes by methods. Adapt monitors.
Restructure wake field implementation.

    - User generates wakes using wake_fields_3.py interface.
    - A wake source generates a list of wake kick objects.
    - Tracking is done in wake_fields_3.py for all the kick objects
      for all the wake sources that are provided by the user.
Open and close h5 monitor files at each 'dump' -> Data are stored even when simulation crashes.

  - No large performance penalty observed.
Variables z_index and first_particle_index_in_slice stored exactly the same information -> reduce to one.
Rename classmethod 'wake_table' -> 'table'.
Allows user to set Yokoya factors in classmethod 'resistive_wall'.
Fixes naming bug (variable 'resistive_wall_length') in ResistiveWall class.
Adds three basic tests for wake fields (from table, resonator, resistive wall).

    - dipX, dipY, quadX, quadY kicks at turn 5 are compared to old, benchmarked
      results (former implementation of wakes in PyHT) read from files.
    - Bunch initial distribution is read from file.