move down init

Add requirements.txt for pip install
Update mbtrack2.yml to add accelerator-toolbox dependency for lattice import

Fix plot_phasespacedata and plot_profiledata
Change color map for streak plots for plot_profiledata, plot_wakedata, plot_cavitydata

Add utilities and instability folders
Change folder name from collective_effects to impedance

Remove untested code
Rename BeamLoadingVlasov to BeamLoadingEquilibrium

Change wake function in CircularResistiveWall to enforce fundamental theorem of beam loading.
Rework Resonator class to set manually time and frequency arrays and enforce fundamental theorem of beam loading.
Change to WakeField.impedance_components and WakeField.wake_components to allow methods begining by W or Z in WakeField subclasses.

Multiple hdf5 file can now be made without having to use MPI. This is achieved by clearing the file name storage every time the monitor is closed.

Changing Ncav after initialization now change the total shunt impedance Rs

Change beam_equilibrium to allow to minimize center of mass offset instead of energy balance.

New LongRangeResistiveWall class to deal with multi-bunch and multi-turn wakes from resistive wall.
Add Mpi.share_means method to share bunch means using MPI.

Allow to plot detuning, tuning angle and powers from tracking.

Add Ncav parameter and Rs_per_cavity attribute to remove ambiguity about what should be used
Add attributes and methods to compute Pc, Pb and Pr.
Add method to set optimal coupling value.

Correct typo in ion_frequency

Fix error on plot_beamdata.
Add option to specify ylim to streak_bunchspectrum and to streak_beamspectrum.

Fix TD calculation for transverse dipolar wakes due to sign change in the 31/08/2021 commit.

Add a is_empty property to the Bunch class.
Add a check_empty optional parameter to the Monitor.track_bunch_data method.
ProfileMonitor: if the bunch is empty, no profile is saved.
WakePotentialMonitor: if the bunch is empty, the same from last good turn is saved.
BunchSpectrumMonitor: if the bunch is empty, the incoherent spectrum is nan.

libver='earliest' allow for better backward compatibility when switching HDF5 versions.

Convert h5py data into numpy arrays as fancy indexing is broken in h5py >= 3.1.0

Fix approximated longitudinal wake function sign in CircularResistiveWall

Correct scale for the exact TransverseWakeFunction in CircularResistiveWall.
Thanks to Keon Hee Kim for providing the correction factor.