New HID report item macros (with HID_RI_ prefix) to allow for easy creation...

New HID report item macros (with HID_RI_ prefix) to allow for easy creation and editing of HID report descriptors.

Changed over all project and demo HID report descriptors to use the new HID report item macros.

Moved the HIDParser.c source file to the LUFA/Drivers/USB/Class/Common/ directory from the LUFA/Drivers/USB/Class/Host/.