OpenSystemsDevelopment / qpdf

…`warn`, streamline condition handling.

Replace data member oh with accessors.

Remove redundant overloads from QPDFObjGen::set.

I decided these were confusing and inconsistent with how JSON works.
They muddle the API rather than improving it.

Change .clang-format and commit automated changes from a fresh run of
format-code

Run this:

for i in  **/*.cc **/*.c **/*.h **/*.hh; do
  clang-format < $i >| $i.new && mv $i.new $i
done

Use QPDFObjectHandle::isNameAndEquals, isDictionaryOfType and
isStreamOfType.