[Nut-upsdev] HID parser improvements

[Peter Selinger]

I just committed a change to the HID parser. I have changed the API so
that the report descriptor gets parsed into a data structure once,
rather than being re-scanned as a byte array all the time. This should
greatly enhance the efficiency of the HID code. It will also make the
code more maintainable, because the new API represents the report
descriptor as an immutable data structure, rather than a mutable
"parser state".

The change is between tags before_PSE_12 and after_PSE_12, see

cvs diff -u -r before_PSE_12 -r after_PSE_12

Note: the change affects newhidups and mge-shut. I have tested
newhidups, but mge-shut still needs to be tested. 

-- Peter