Edc timing

Extend the standalone_edc process to pull timing from an external model's shared memory area or use the gpstime driver.

This adds the --sync-to argument which is the name of the mbuf to read time from. It reads from a rmIpcStr structure and so is suitable to read from an iop. When this is enabled no delays are honored in the standalone_edc and it does not read the timing card. Otherwise it uses the gpstime driver for time.

Marked as WIP until it has had a few more hours of test time on X2.