cornerstone-v1.0.0

• Breaking: CornerstonePersistentRepositoryMixin's loadData() is now removed. You just need to add dependency of convertToSnapshot to persistent repository with CornerstonePersistentRepositoryMixin. The mixin now handles loading data, and assigning it to repo.snapshot (Means less code to write!). The snapshot is now named snapshot, and declared in the mixin (you can override it). If you want to use other names for snapshot, you need to override load. You can override snapshot if you want to assign default value to it (See auto_persistent_people_repository.dart in example).
• First stable release of cornerstone! From now on, breaking changes will only introduced with new major version.