Improve docstrings for IIR in ProportionalIntegralLoop.
Modify CavityResonator.is_CBI_stable to use  lcbi_growth_rate.
Update lcbi_growth_rate_mode, lcbi_growth_rate and lcbi_stability_diagram to optionally take  synchrotron_tune as input.

Add form factor option to set_optimal_detune.
Fix priniting in BeamLoadingEquilibrium.

interp_on_postion=False allows for faster tracking but the wake potential is interpolated on the bin center and each particle of the bin get the same value.

Update gitignore

Change the way Bunch particles coordinates are stored and accessed.
Speed-up TransverseMap.
Refactor WakePotential. 

Fix resonator wake function for negative time and update docstrings.

Synchrotron.to_pyat retrun a pyAT simple_ring element.

Fix to_pyat

Update mbtrack2.yml
Remove requirements.txt

Add poetry.lock file
Fix imports in feedback.py

Update CavityResonator and collective effects notebooks.

Remove IQ mentions in ProportionalIntegralLoop as not implemented yet.
Add delay < 1 error in ProportionalLoop.
Addition referece for DirectFeedback docstring.

Get back to previous behaviour with plot_type="bunch" as default.

Improve ProportionalIntegralLoop & DirectFeedback docstrings.

Bug fix in plot_cavitydata.
New method to sample the voltage seen by a zero charge particle during an RF period.

Add update_feedback method to CavityResonator to force FB update when needed (when QL or tuning is changed).
The feedback reference targets (setpoints) for ProportionalIntegralLoop is now CavityResonator Vc and theta as for ProportionalLoop.
Add an init_FFconst method to ProportionalIntegralLoop which is called at initialization only (not any more after each setpoint change) and needs to be called manually if we want to change the feedfoward constant during tracking.
Some simplifications on the expressions in ProportionalIntegralLoop.
CavityMonitor now records Vc and theta.
Add option "mean" to plot_cavitydata to plot the mean phasor voltage and angle versus time for non empty bunches (now the default behaviour).
Add optinal parameter show_objective to cavitydata, if True shows the Cavity voltage and phase objective value in plots.

Remove matrix optional parameter from ProportionalIntegralLoop. Always use the matrix method as the formuma method does not give results as good as the matrix method (leads to voltage/phase oscillations).

Fix lcbi_growth_rate_mode, effective_impedance and head_tail_form_factor to be use new form of eta.