InverseOperatorResult::clear() does not reset condition_estimate

!102 (merged) added a condition_estimate member to InverseOperatorResult, but failed to implement resetting it in InverseOperatorResult::clear().

created branch 39-inverseoperatorresult-clear-does-not-reset-condition_estimate

mentioned in merge request !158 (merged)

closed via merge request !158 (merged)

closed via commit 55b6f9ea

mentioned in commit 55b6f9ea