OpenSystemsDevelopment / qpdf

Apply various Clang-Tidy rules

Using search and replace.

Set indent differently for qdf and non-qdf files.
Combine with preceding newline for qdf files.

Also, uninitialize QPDFWriter::Members members.

Use string_view parameters and call pipeline write methods directly.

Move test for m->linearized outside loop.

I decided that it's actually fine to copy a direct object to another
QPDF. Even if we eventually prevent a QPDFObject from having multiple
parents, this could happen if an object is moved.

For consistency with similar methods, e.g. replaceObject.

Code tidy : replace 0 with nullptr or true

Remove any ambiguity around whether old or new value is being
returned.

Also, revert inlining of unparse and operator << from commit 4c6640c in
order to avoid exposing QUtil.

Remove variables obsoleted by commit 4f24617.

Prevent my future self or other contributors from using assert in
tests and then having that assert not do anything because of the
NDEBUG macro.

Where not possible, use "auto" to get the iterator type.

Editorial note: I have avoid this change for a long time because of
not wanting to make gratuitous changes to version history, which can
obscure when certain changes were made, but with having recently
touched every single file to apply automatic code formatting and with
making several broad changes to the API, I decided it was time to take
the plunge and get rid of the older (pre-C++11) verbose iterator
syntax. The new code is just easier to read and understand, and in
many cases, it will be more effecient as fewer temporary copies are
being made.

m-holger, if you're reading, you can see that I've finally come
around. :-)

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