Simplex Warmstart

[nathanneike]

…omputed potentials from sinkhorn or even related simplex

Types of changes

Add Warmstart intialisation to the simplex solver allows us to give good potentials to our solvers and get why faster to solution with less iterations.

Motivation and context / Related issue

This change allows us to warmstart with potentials from other solvers. Instead of using normal initial pivots to create a Tree. We use the given potential to create a first feasible solution in our Simplex. If given potentials are good potential for big speedup. Still need to compute all Reduce Costs at least once which means that the running time for the warmstart can be big for big problems so should be done with good potentials and not just any potentials.

How has this been tested (if it applies)

Not yet still needs to be done in the test directory.

PR checklist

• I have read the CONTRIBUTING document.
• The documentation is up-to-date with the changes I made (check build artifacts).
• All tests passed, and additional code has been covered with new tests.
• I have added the PR and Issue fix to the RELEASES.md file.