Usually in SAT solving, the conflict clause has at least two false literals at the max level (otherwise, the last literal would have been propagated at an earlier level).
But here we are adding clauses on demand; so after backtracking we may have the case that the conflict clause has exactly one undefined literal that must be propagated explicitly.
* conflict_core doesn't need gc() anymore
* update comments, ensure_bvar for new constraints
* Make sure constraints can only be created through constraint_manager
* fix constraint::display if no boolean variable is assigned
* Move clause into separate file
* Add conflict_core binary resolution
* conflict_core additions
* reactivate conflict resolution outer loop
* wip
* seems commented includes break CI build
