OpenSystemsDevelopment / qpdf

Clang seems to be slightly stricter than gcc.

Have classes contain only a single private member of type
PointerHolder<Members>. This makes it safe to change the structure of
the Members class without breaking binary compatibility. Many of the
classes already follow this pattern quite successfully. This brings in
the rest of the class that are part of the public API.

Based on sizeof(size_t). Assumes 64 if not 32.

Since autogenerated files are now committed, we no longer need to
rerun ./autogen.sh and actually shouldn't because it could mask
errors.

gcc already warns for undefined variables, but this is in preparation
for Google's oss-fuzz, which builds in this way.

The Azure pipeline does all the artifact creation now.

Since the files autogen.sh creates are now controlled, you only have
to run autogen.sh when you modify the source files, not when you
build from a clean checkout.

Update documentation to reflect that automatically generated files are
committed. Detect when they are outdated if we have the ability to
regenerate them.

Update this to be a more accurate reflection of what I actually do and
to make it a better and more usable checklist.

This is how I work with the file, so this format is most convenient
for me.