[breaking] a large refactoring of MathOptIIS

This commit is breaking because it:

 * Removes SkipFeasibilityCheck
 * Removes StopIfInfeasibleBounds
 * Removes StopIfInfeasibleRanges
 * Removes DeletionFilter
 * Removes ElasticFilterTolerance
 * Removes ElasticFilterIgnoreIntegrality

In addition, this commit will likely result in a different IIS being
returned for many models because it now exploits an infeasibility
certificate if one is present.

Author: odow