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

Add bunch_X properties to Beam class
Add a generator over "not empty" bunches to Beam class
Modify Bunch class in order to have mean, std and emit as property and not method

Empty bunches are now not None any more but represented by Bunch class with 1 mp set to dead
Change init_beam to reflect the change

Empty bunches are now not None any more but represented by Bunch class with 1 mp set to dead
Change init_beam to reflect the change

Use pandas DF to hold data in Bunch class instead of numpy masked array -> better behaviour and allows to set to alive particles only