Xtrack

**Changes**
- Add possibility to log variables and other quantities at each turn.
- Add possibility to extract a view on the merit function from Optimize objects
- Adapt to updated nafflib.

**Full Changelog**: https://github.com/xsuite/xtrack/compare/v0.51.0...v0.51.1

**Changes:**
- Second order dispersion and second order chromaticity added to twiss result.
- Add chromatic properties to allowed keyword arguments for optimization targets.
- Search for off-momentum closed orbit when computing chromatic properties in twiss.
- Closed orbit search performed with Jacobian optimizer instead of numpy fsolve.
- Possibility to use the optimizer on a generic callable.
- Implement solenoid backtrack.

**Full Changelog**: https://github.com/xsuite/xtrack/compare/v0.50.1...v0.51.0

**Changes:**
- Change names in tracking loop counters to avoid name clashes.
- Sort class names alphabetically when building tracker.

**Full Changelog**: https://github.com/xsuite/xtrack/compare/v0.50.0...v0.50.1

**Changes**
- Yoshida integrator implemented within `Bend` elements, providing accurate model for combined function magnets. Users can choose model among `adaptive`, `expanded`, `bend-kick-bend`, `rot-kick-rot`. The default model becomes `adaptive` which computes uses the `rot-kick-rot` scheme with a number of Yoshida slices adapted to the bend curvature.
- Removed `CombinedFunctionMagnet` which can now be modeled by a `Bend`.
- Removed multipolar_kicks from `Quadrupole`.
- Implemented `Line.get_non_linear_chromaticity(...)`

**Full Changelog**: https://github.com/xsuite/xtrack/compare/v0.49.0...v0.50.0

**Changes**
- Add method `EnergyProgram.get_kinetic_energy0_at_t_s(...)`.
- Add method `Line.get_amplitude_detuning_coefficients(...)`.
- Change `Line.twiss(...)` argument names: `ele_start` becomes `start`, `ele_stop` becomes `end`, `twiss_init` becomes `init`, `ele_init` becomes `init_at`, `ele_co_search` becomes `co_search_at`.
- Renamed `TwissTable.betz0` to `TwissTable.bets0`.
- xdeps manager initialized by default when creating a line.
- Add possibility to define optimization targets from line or vars through `Line.target(...)` or `Line.vars.target(...)`.
- Add possibility to define optimization targets from existing twiss tables through `TwissTable.target(...)`.]
- In Line.match remove `preserve`, `preserve_start`, `preserve_stop`, user can pass a twiss table instead.
- Add method `Optimizer.tag(...)`.
- Remove `LinearTransferMatrix` (was already deprecated).
- Rename amplitude detuning coefficients in the `LineSegmentMap` element (`detx_x` becomes `det_xx`, `detx_y` becomes `det_xy`, etc…).
- Thick elements allowed by default when importing from MAD-X.
- Add dependency on pandas.
- Improvements and updates in many examples.

**Full Changelog**: https://github.com/xsuite/xtrack/compare/v0.48.2...v0.49.0

**Changes:**
* Fix issue with reference energy change in `LineSegmentMap`

**Full Changelog**: https://github.com/xsuite/xtrack/compare/v0.48.1...v0.48.2