Added new USE_FLASH_DESCRIPTORS compile time option. By default, descriptors can now lie in mixed memory spaces (specified by a new parameter to the CALLBACK_USB_GetDescriptor() function) unless one of the USE_*_DESCRIPTORS compile time option is specified.
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.
Split out common defines/types from class drivers into a seperate common class driver directory.
Make central USB Class driver dispatch headers, used for both device and host modes.