Initial implementation of repository conflicts.
Implement conflicts file output.
Fix bugs with conflicts detection logic.
Fix bugs in conflicts detection algorithm.
Add the cleanup of conflicts structures.
Cleanup temporary db as well.
Rework conflicts system.

Add emitting of conflicts to a manifest.
Add loading conflicts from a manifest.
Add utility functions to operate with conflicts.
Make conflicts a hash table.
Rework and simplify conflicts detection logic.
Fix SQL queries.
Add new schema for provides and conflicts.