v1.3.6:
 - fixed sky_to_pole() tests and a couple other tests
 - fixed a bug with output_handler.make_nbody_input() not writing '\n' at end of file

v1.3.5:
 - sky_to_pole() now uses a change of basis matrix instead of vector math
 - fixed bugs with mismatches of Timestep.index_list after extra calculations
 - Timestep.id is now an array of ints, not floats
 - added Timestep.take_by_id()
 - output_handler.make_nbody_input() now properly handles the 'recenter' keyword argument
 - output_handler.make_nbody_input() pads now floats correctly
 - updated README
 - Timestep.typ is now a list of ints, not floats

v1.3.4:
 - Timestep.typ attribute stores whether particles are baryons (0) or dark matter (1)
 - output_handler has been updated to also read in particle type
 - Timestep.only_baryons() and Timestep_only_dark_matter() cut the data to only
   include one type of particle
 - Added support for galactic spherical coordinates (phi, theta)
 - Added find_progenitor()
 - make_nbody_input() no longer recenters the Timestep before printing out
 - fixed 'self not defined' error in output_handler.make_csv()
 - Timestep.rad and Timestep.rot are now Timestep.vrad and Timestep.vrot
 - updated documentation pdf to new naming convention
 - updated documentation to include all supported functions
 - updated README
 - removed coords.approx_lsr()

v1.3.3:
 - added changelog
 - fixed bug in Timestep.copy() that would cause error if the Timestep had calculated values
 - adapted python standard naming convention (mostly, method names went from camelCase to lower_case)
 - consolidated coords.py tests into tests.py
 - bug fix in coords.cart_to_plane()
 - fixed import scheme
