Extend FastPiecewise to discontinuous functions
Add testcases to FastPiecewise
First version of general minimality test
First version of simple extremality test
Next version of general minimality test
(FastPiecewise): Add which_function.
(FastPiecewise.which_function): Add tests; two currently fail
(plot_covered_intervals): Handle discontinuous case
Fix a bug in minimality_test_general.  Make fewer tests when there is some continuity.
Fix a bug in FastPiecewise.which_function
(FastPiecewise.limit): Add testcases
Fix testcase output
Reimplement FastPiecewise.limit in terms of new method FastPiecewise.limits
Delete irrational functions (now in extreme_functions_from_literature.sage).  Move multiplicative_homomorphism to new file compendium_procedures.sage
Improve plotting of discontinuity markers for testcase h = FastPiecewise([[singleton_interval(0), FastLinearFunction(0,0)], [open_interval(0, 1/2), FastLinearFunction(6, -1)], [closed_interval(1/2,1), FastLinearFunction(-2, 2)]], merge=False)
Merge branch 'discontinuous_piecewise' of https://github.com/mkoeppe/infinite-group-relaxation-code into discontinuous_piecewise

Conflicts:
	functions.sage
Next rewrite of minimality_test_general
Reimplement generate_nonsubadditive_vertices and generate_additive_vertices in terms of generators. Reimplement minimality_check in terms of generate_nonsubadditive_vertices.
Add didactical equivalent code (commented out).
Add .gitignore