------------------
Added
^^^^^
- ``PiRationalFormatter`` that prints rational multiples of pi.
- ``zero_props`` and ``pole_props`` argument to ``plane_plots.*plane*``-functions
that allows more detailed styling of pole/zero markers.
- ``multiplicity_props`` argument to ``plane_plots.*plane*``-functions that allows
styling of pole/zero multiplicity texts.
- This changelog.
Fixed
^^^^^
- ``freq_unit`` was not propagated properly in all ``freq_plots.zfreq*`` functions and
``style``-combinations.
Changed
^^^^^^^
- Change to src-layout