Xpart version 0.3.0

New features:

• Generation of halo and pencil distributions.
• Particles.to_dict creates by default a copy of the data on CPU.
• Introduced Particles.merge and Particles.filter methods.
• Introduced Particles.to_pandas and Particles.from_pandas methods.
• Introduced examples on how to save/load particles from/to file.
• build_particles and generate_matched_gaussian_bunch can find automatically the closed orbit and the one-turn matrix from a xtrack.Tracker object.
• Introduced explicit modes (set, shift, normalized_transverse) as input of the build_particles function.
• generate_longitudinal can use a xtrack.Tracker object to find the required machine parameters (RF voltage, harmonics, phases, momentum compaction factor).

Fix

• In the Particles.from_dict method all energy variables are taken from the dictionary (before they were all recomputed from delta)