c04cceb40e
Correctly reset `prev` and `next` pointers of action group FCurves when separating them into distinct `ListBase`s per `bActionGroup`. These `NULL` pointers are necessary to temporarily demarcate the start & end of the `bActionGroup::channels` list. Having them still point to other FCurves caused ordering issues when moving curves towards the start/end of a group. This commit corrects the above issue and adds versioning code to rectify any ordering issues that may have been caused. For this purpose the `BKE_action_groups_reconstruct()` function is rewritten to avoid relying on the `bAction::curves` list order or `prev` link integrity. Differential Revision: https://developer.blender.org/D11811