Update to solve and solver

There's a function that can find the penalty of a task machine pair
Revert "Update to solve and solver"

This reverts commit 370ef74d67c04241042e5cae19255ffb3573d7fd.
Merge remote-tracking branch 'origin/master' into nigel2
Merge remote-tracking branch 'origin/nathan' into nigel2
Merge remote-tracking branch 'origin/master' into nigel2