Completed host CDC class driver enumeration code.

Added new TOTAL_NUM_CONFIGURATIONS option, removed USE_SINGLE_DEVICE_CONFIGURATION compile time option (but silently convert it to USE_SINGLE_DEVICE_CONFIGURATION internally for compatibility).

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.

Added new HOST_STATE_WaitForDeviceRemoval host state machine state for non-blocking disabling of device communications until the device has been removed (for use when an error occurs or communications with the device have completed). Changed over all host mode demos to use the new state.

Added verbose documentation for each of the USB Host state machine states.

Added parameter directions to function parameter documentation.

Added new experimental FAST_STREAM_FUNCTIONS compile time option to speed up stream transfers at the expense of a higher FLASH consumption (needs testing to verify improved throughput).

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.

Pipe_ConfigurePipe() now automatically defaults IN pipes to accepting infinite IN requests, this can still be changed by calling the existing \ref Pipe_SetFiniteINRequests() function.

Added USE_INTERNAL_SERIAL compile time option to automatically read out the internal unique serial number as the device's serial number descriptor on supported AVR models.

Extend USB_GetDeviceConfigDescriptor() routine to require the configuration number within the device to fetch, to add support for multi-configuration devices.

Re-add in simple scheduler for compatibility with legacy code, mark all scheduler related files as deprecated.

Break device mode class driver interfaces into seperate config and state structs which are then combined, for clarity. Move device mode class driver interfaces back into the device mode class driver headers from the common class headers to make room for host class interfaces.

Enhanced class drivers to use the same public/private section seperations as other portions of the library.

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.

Commit of new class abstraction APIs for all device demos other than the MIDI demo - not documented yet.

Removed scheduler and memory allocation libraries.

Added new EVENT_USB_StartOfFrame event in the library to indicate the start of each USB frame (when generated).

Removed Tx interrupt from the USBtoSerial demo; now sends characters via polling to ensure more time for the Rx interrupt.