Added auxillary SerialBE, SerialLE, and SerialHost type classes
baseline Serial instances defined with SerialBE when possible
Export list expanded to include auxiliary classes
Added module doc for Data.Bytes.Serial
clarified some other documentation
Better module intro documentation
Added `Generic` helper classes and default instances for SerialBE and SerialLE
SerialHost is given default instance from either SerialBE or SerialLE
The choice between those two classes is made with CPP