OpenSystemsDevelopment / qpdf

When there is no context for writing output or error messages, use the
default logger.

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

Run this:

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

The executables that libtool built invoked the underlying binary with
an "lt-" prefix. The code contained numerous workarounds for testing,
which can now be removed.

This was unintended behavior that was added back for backward
compatibility. It is intentionally undocumented.

This comment expands all tabs using an 8-character tab-width. You
should ignore this commit when using git blame or use git blame -w.

In the early days, I used to use tabs where possible for indentation,
since emacs did this automatically. In recent years, I have switched
to only using spaces, which means qpdf source code has been a mixture
of spaces and tabs. I have avoided cleaning this up because of not
wanting gratuitous whitespaces change to cloud the output of git
blame, but I changed my mind after discussing with users who view qpdf
source code in editors/IDEs that have other tab widths by default and
in light of the fact that I am planning to start applying automatic
code formatting soon.

* Use unique_ptr in place of shared_ptr in some cases
* unique_ptr for arrays does not require a custom deleter
* use std::make_unique (c++14) where possible

This makes it much more convention to use the initializeFromArgv
functions since you can use string literals.

This was used, but it no longer is, so let's not keep the extra
complexity around.

Also fix QPDFArgParser

This is a massive rewrite of the help text and cli.rst section of the
manual. All command-line flags now have their own help and are
specifically index. qpdf --help is completely redone.

Handle optional choices in addition to required choices. Refactor the
way help options are added to completion to make it work with optional
help choices.

Move ArgParser from qpdf.cc into QPDFJob.cc. It still works with
millions of public member variables, but now qpdf.cc is minimal and
just calls stable library functions.

Move most of the methods called from qpdf.cc after argument parsing
into QPDFJob. In this increment, enough QPDFJob API has been added to
handle the branch of QPDFJob::run() that creates output with an
appropriate division between qpdf.cc and QPDFJob.

There are temporary bits of code to enable everything to compile and
pass the test suite, including some duplication and hard-coded values.