OpenSystemsDevelopment / qpdf

If /AP is a dictionary of streams rather than a dictionary of
dictionaries, disregard /AS, which is supposed to point to a subkey of
one of the dictionaries. This fix prevents qpdf's annotation
flattening from discarding some annotations when /AS is erroneously
set.

Add new method QPDF::newReserved()

Switch output to QDF for easier diffing
Simplify input image
Reduce decimal places

This works around an issue were, for certain versions, the mingw32
tests failed because of irrelevant floating point rounding issues in
the test output.

Add new convenience class QPDFObjGen::Guard

Code tidy