Xtrack version 0.25.0

Changes:

• Possibility to use prebuilt kernels instead of compiling just in time.
• In tracker.compensate_radiation_energy_loss added record_iterations flag.
• Added Marker element type and modified mad loader to use markers instead of zero-length drifts.
• In line optimizers, added possibility of preserving all markers or selected ones.
• Added Line.from_sequence constructor.
• Added some missing backtracking elements.
• Added "exact" drift mode.