OpenSystemsDevelopment / qpdf

When a QPDF is destroyed, changing indirect objects to direct nulls
makes them effectively disappear silently when they sneak into other
places. Instead, we should treat this as an error. Adding a destroyed
object type makes this possible.

Allow QPDFObjectHandle::obj to be set prior resolving object.

ot_unresolved has been appended to the list object types in order to
preserve the output of existing test cases.

Not fully exercised in this commit

Run this:

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

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.

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.

They have to be ot_* rather than qpdf_ot_* for compatibility.

* Different enumerated types are not assignment-compatible in C++, at
  least with strict compiler settings
* While you can do `constexpr ot_xyz = ::qpdf_ot_xyz` in QPDFObject.hh to
  make QPDFObject::ot_xyz work, QPDFObject::object_type_e::ot_xyz will
  only work if the enumerated type names are the same.

Setting encryption permissions for R >= 3 set permission bits in
groups corresponding to menu options in Acrobat 5. The new API allows
the bits to be set individually.

The Apache License version 2.0 is now the primary license for qpdf.
However, users may, at their option, continue to use Artistic version
2.0.

This commit adds several API methods that enable control over which
types of filters QPDF will attempt to decode. It also adds support for
/RunLengthDecode and /DCTDecode filters for both encoding and
decoding.

Also add copyright notice to a few public headers that were missing
one.

git-svn-id: svn+q:///qpdf/trunk@1051 71b93d88-0707-0410-a8cf-f5a4172ac649

git-svn-id: svn+q:///qpdf/trunk@935 71b93d88-0707-0410-a8cf-f5a4172ac649

git-svn-id: svn+q:///qpdf/trunk@901 71b93d88-0707-0410-a8cf-f5a4172ac649

git-svn-id: svn+q:///qpdf/trunk@894 71b93d88-0707-0410-a8cf-f5a4172ac649