Re-added Pipe_IsEndpointBound() calls to the CDC and RNDIS host class drivers, not that the function has the correct behaviour for devices with bidirectional endpoints.

Fixed CDC and RNDIS host demos and class drivers - bidirectional endpoints should use two seperate pipes, not one half-duplex pipe.

Inline USB management functions in the Class drivers which are standardized but currently unused, to prevent them from using up unneccesary cycles and flash in the user application.

Correct CDC Host Class driver token handling for sending data on bidirectional data endpoints.

Fixed all Class drivers to ensure they have appropriate guards on each function to ensure the device is enumerated before running, fixed error codes on all guards to return "DeviceDisconnected" where possble.

Renamed HOST_SENDCONTROL_DeviceDisconnect enum value to HOST_SENDCONTROL_DeviceDisconnected to be in line with the rest of the library enum error codes.