New features:
* fast mode for 2d structure factor implemented
* `replace_frame` added to BaseTrajectory
* cluster-resolved kinetic temperature added
* real fft and spectrum added
* axis line width and tick width added to `amep.plot.format_axis`
* cluster-resolved msd added
* `linear_mappable` added
* radius of gyration added
* `get_ids()` added to BaseFrame
* `in_circle` added
* cluster-resolved calculation of the number of next neighbors added
* `ClusterFraction` added
Bug fixes:
* small bug fixed in `pbc.pbc_points`
* bug in `traj.get_forces()` fixed
* bug in loading LAMMPS data fixed
* saving results of evaluate objects now possible with user-defined file name
Contributors:
* Lukas Hecht