Fix to previous patch (make CDCHost demo deallocate pipes when an invalid CDC interface is skipped).

Remove the saving of the USB_GetNextDescriptorComp() return value in all host demos, since it went unused anyway; replaced with a simple check against the success error code for clarity.

Fixed incorrect HID interface class and subclass values in the Mouse and KeyboardMouse demos (thanks to Brian Dickman).

Capitolised the "Descriptor_Search" and "Descriptor_Search_Comp" prefixes of the values in the DSearch_Return_ErrorCodes_t and DSearch_Comp_Return_ErrorCodes_t enums.

Minor documentation improvements.

Removed "Host_" section of the function names in ConfigDescriptor.h, as most of the routines can now be used in device mode on the device descriptor.

Renamed functions in the HID parser to have a "USB_" prefix and the acronym "HID" in the name.

Further module-level documentation updates.

Seperated out OTG, Device and Host mode demos into seperate folders for clarity. Adjusted makefiles so that the path to the LUFA library can be set in one place.