Module migrations

Migrate the reference counting state.

Traits

• V2ToV3
  Trait to implement to give information about types used for migration

Functions

• migrate_from_dual_to_triple_ref_count
  Migrate from dual u32 reference counting to triple u32 reference counting.
• migrate_from_single_to_triple_ref_count
  Migrate from unique u32 reference counting to triple u32 reference counting.
• migrate_from_single_u8_to_triple_ref_count
  Migrate from unique u8 reference counting to triple u32 reference counting.