Support RETDAT_INIT/RETDAT_CANCEL consistently
MOOC defines two methods,
RETDAT_CANCEL, so that an object can set-up and tear down resources to handle a request. This issue will track efforts ensuring MOOC consistently uses these, and other, equivalent methods:
- If FTPMAN is going to use the RETDAT method (i.e. the request is periodic at 15 Hz, or slower) it should call these methods (if it doesn't already.)
- Higher-speed FTP and SNAP plots need to have set-up tear-down routines. If they already don't, they should be added.
- Alarm scans should call these methods when an object is added to or removed from their list.