make vector field density independent of domain size
scaled plots during discretization
refactor plot_partition
extract plot_transition_arrow from plot_partition
new args: hatch, alpha of Polytope.plot, Region.plot
new: Polytope.text, Region.text
plot arrow between polytopes during reachability check
plot hatched and annotated continuous propositions during partitioning
change polytope color and improve comments
use Region.text for number annotations in plot_partition