Add more skeleton functions and definitions to the Mass Storage Host mode Class driver.
Made Endpoint_Write_DWord_* functions echo the structure of the matching Endpoint routines for clarity.
Added ATTR_NON_NULL_PTR_ARG() attributes to the class drivers to improve user code reliability by disallowing explicit NULL pointers as pointer parameters in function calls where the parameter must not be NULL.
Disabled building of the Demos/Host/ClassDriver directory until Host Mode Class drivers are complete to prevent build errors in the meantime.
Remove all Host mode class demos other than the CDCHost class driver demo, so that they can be re-added as they are made once the host mode class framework is designed.
Fixed USB_Host_SendControlRequest() not re-suspending the USB bus when initial device ready-wait fails.
Fixed USB Pad regulator not being disabled on some AVR models when the USB_OPT_REG_DISABLED option is used.
Dean Camera