Change back invariant name to cs_invariant
Simplify SkewQuadrupole track method

Compared to mbtrack, the head/tail convention is reversed which leads to this sign change.
In this python code, the head is for negative times, t<0.
The sign change allows successful tracking benchmark with mbtrack for pure inductive and resonator impedance

Add transverse wake potential to WakePotential and move class to dedicated file
Merge Resonator and TransverseResonator into Resonator with dedicated file
wakefunction_from_imp -> change trimming to allow for a float value
wakefunction_from_imp -> transverse impedance divided by 1j, to be checked with impedance convention but ok with benchmark
Wakefield -> add wake_components

- Deconvolution methods in WakeFunction and Impedance class were improved.
- Analytical impedance calculation method was added to Resonator class.
- Wake potential calculation method in WakePotential2 class was corrected.

- New Wakefunction class to store a wake function object.
- New deconvolve_wp and deconvolve_imp methods were added in Wakefunction class.
- New  get-impedance method was added in Impedance class.
- New Resonator class to calculate the analytical resonator wake function.
- New Wakepotential2 class to take in wake function objects, then compute the wake potential and do the tracking.

- New Wakefunction class to store a wake function object.
- New deconvolve_wp and deconvolve_imp methods were added in Wakefunction class.
- New  get-impedance method was added in Impedance class.
- New Resonator class to calculate the analytical resonator wake function.
- New Wakepotential2 class to take in wake function objects, then compute the wake potential and do the tracking.

Remove tools.py to avoid circular import problem with wakefield.py -> merged into wakefield.py
Remove machines folder to save machine data in a seperate git instance
Rework import so the code can be used as independant module mbtrack2

Adding a class for tracking wake potential

Optic functions as arrays
Uses PyAT lattice for import
Adapt other files for the change

Update machines/__init__.py, machines/soleil.py, tracking/__init__.py, tracking/aperture.py, tracking/element.py, tracking/optics.py, tracking/parallel.py, tracking/particles.py, tracking/rf.py, tracking/synchrotron.py files

To be PEP8 complient:
Lowercase folders
Extended docstrings
Rename and divide some files

Add synchrotron radiation in transverse plane
Fix a mistake in the transverse one turn map

New parallel module to handle Mpi class which is used in Beam

Test OK, to improve