InteractiveLPProblem: refactor plot method

[mkoeppe]

This is preparation for #18805 - Add didactical implementation of tableau cutting planes to interactive_simplex_method
and in fact split out from the larger patch there.

While preparing this patch, I noticed that the code in current Sage is not able to plot some LPs with irrational data (this is now #21270).
The code on this ticket does not fix this; it actually has a different failure mode for this example.

CC: @pgxiao @novoselt

Component: linear programming

Author: Peijun Xiao

Branch/Commit: u/mkoeppe/interactivelpproblem__refactor_plot_method @ aa3fa4b

Issue created by migration from https://trac.sagemath.org/ticket/20570

[mkoeppe]

Branch: u/mkoeppe/interactivelpproblem__refactor_plot_method

[mkoeppe]

New commits:

2ac4760	InteractiveLPProblem: Refactor plot using new methods get_plot_bounding_box and plot_objective_growth_and_solution
0416add	Minor cleanup
aa3fa4b	Add testcase for plotting of irrational polygons

[mkoeppe]

Commit: aa3fa4b

[novoselt]

comment:3

If you have found a bug in polyhedron code, please open a ticket to fix it!

[mkoeppe]

comment:4

Replying to @novoselt:

If you have found a bug in polyhedron code, please open a ticket to fix it!

Could be related to #18220

[mkoeppe]

comment:5

Replying to @novoselt:

If you have found a bug in polyhedron code, please open a ticket to fix it!

This is now #21270.