Discrete omega-damping plot and tweaks#193

Merged

murrayrm merged 5 commits intopython-control:masterfrom

Sup3rGeo:zgrid-cherry

Dec 28, 2018

Commits on Feb 19, 2018

Added discrete grid to pzmap function.
Victor
committed
Revert "Added discrete grid to pzmap function."
Victor
committed
Added discrete grid to pzmap function.
Victor
committed
Tweaked axis lines and zero/pole markers.
Victor
committed

Commits on Mar 11, 2018

Refactored sgrid based on matplotlib projections and moved sgrid and zgrid to new python module.
victor
committed