Abstract Calendaring API

We need a full "CRUD" (Create/Read/Update/Delete) Abstract Application Programming Interface and Calendaring Architecture for Calendaring and Scheduling.

An Abstract Calendaring API from which fully compliant interfaces can be created will enable "Calendaring as a Platform" — that is, any process running on a system can use the API to perform calendar and scheduling operations against any calendaring and scheduling implementation running on that system.

Work item of: TC API.