Pyheadtail

New feature:
- Synchrotron radiation module with corresponding test scripts

- Add verbose mode in synchrotrons to print attributes of one turn map. Useful for inspection since often some kwargs are not actually passed through to the objects using them.

- Improved slicing:
- SliceSet: introduced particles_outside_cut
- Particles: indeces handled correcly by: **add**, **radd**, and extract_slices
- Particles: include_non_sliced functionality added to extract_slices
- For lepton simulations
- Better estimate of Q_s in generate_6D_Gaussian_bunch
- Longitudinal tracking and matching work with negative charge
- Added CLIC-DR example with electrons

- Hotfix: import error in LHC example
- Few extra features added to synchrotron (should be backwards compatible):
- RF can be placed in the middle or at the end of the one turn map
- extra keyword to pass arbitrary detuners on top of Q' and anharmonicities
- explicit disable for cython transverse map

- Particles: added z_beamframe attribute for space charge calculations.
- Particles: make z_beamframe settable
- Make _version.py git evaluation comply with PEP440.
- Using Makefile instead of unclear ./install script.
- Make generators and Particles conform with the Printing interface!
- Adding SilentPrinters to tests and making test_particles work …
- versioning: only amend 4th number if different from master version! …
- Introduced extract_slices method
- m_p has been eliminated
- Introduced machines.synchrotron...

Changes:
- new interface for TransverseMap: removed circumference, detuners are an explicit list
- Particles instances can now be added. E.g.: beam3 = beam1 + beam2 (useful a.o. for multi-bunch studies)
- get_injection_optics method of TransverseMap now returns a dict instead of a tuple