Remove dependancies from the LowLevel demos to the ClassDriver demos, since the use of ClassDriver headers now outputs an error when NO_STREAM_CALLBACKS is used.

Make Low Level host demos use void pointers for the configuration descriptor, to prevent warnings when passed to the altered configuration descriptor parsing routines.

Added preprocessor checks to give a human readable error when the class drivers are used when the incompatible NO_STREAM_CALLBACKS compile time option is used.

Add new manual pages detailing the advantages of LUFA over the official Atmel USB AVR stack, and reasons why LUFA should be used over a built-from-scratch USB stack.