Temporary fix for implicitZero issues.
More fixes.
Fix other sara todos on old tests.
WIP on test, commented out for now.
Fixed lazy inference: in the subproblem we cannot expect anyone to answer if we send a signal, so in any case if anything changes we should schedule ourselves for the next round.
Revert parameters to default. Experimentally the tests don't break with lazyThreshold of 1e-10 or less.
Get rid of the implicitZero, to reinstate it, just revert this commit.
Merge the branch implicitZero-fix with the master.