Add backend for isochronous support for the FSCC cards.
Add C code for setting the clock rate.
Add C code for setting enabling/disabling isochronous mode.
Add init code for isochronous mode.
Fix a couple bugs where SampleRate and EchoCancel might night be populated correctly from the registry.
Fix a bug where the isochronous default was incorrectly set.
Add the ability to get the isochronous value.
Add the ability to get the isochronous value using the C library.
Change the API for get_isochronous.
Add support for isochronous to python.