OpenSystemsDevelopment / qpdf

This change was obviously not supposed to merge.

Enhance 'build-appimage' script:

- add initial comment block and comments for all major steps in the
  script for the benefit of casual users of the script
- 'configure' to build HTML + PDF documentation
- do not remove the man pages from the AppDir (will be used by custom
  AppRun script)
- use a bigger icon
- use '-g' for appimagetool so it can figure out the 'updateinfo' string
  on Travis CI
- output big fat warning to users who build AppImage in non-"Trusty"
  environments

Add 'AppStream' metadata file

This serves to satisfy desktop environments who want to automatically
create menu entries, show screenshots and display software descriptions.

Note, this file (qpdf.appdata.xml) may need more tweaking since the
Freedesktop folks aren't exactly sure themselves how their 'standard'
should exactly look like, and they changed their validation tools
quite a bit over the recent years in incompatible ways...

Extended and enhanced customized AppRun script

- Add a '--ai-usage' invokation param to the AppImage which serves as
  a starting point to explore the other embedded options
- Support displaying of manual pages by running AppImage with added
  parameter '--man ...'
- Also include HTML/PDF documentation, READMEs and licenses into AppImage
- Support for more parameters: '--list-man', '--list-pdf', '--list-readme',
  '--list-license', '--list-html', '--list-exe', '--pdf', '--readme',
  '--license', '--html' and '--show-apprun'
- Support 'fix-pdf' and 'zlib-' as sub-commands (not just as symlinks)

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.

Build in the order that is most likely to detect failures earlier.

Bump to an alpha release. This version is not being widely released
but is being used to push the new shared library version through the
debian packaging system and to test out github releases.

The official, signed AppImage will be build locally for now for
security of my key, but I still want it to be built in a clean,
controlled environment based off a suitably old Linux distribution for
maximal portability in the AppImage.

Hopefully this is it.

The QPDF_String::getUTF8Val() method was not treating strings that
weren't explicitly Unicode as PDF Doc Encoded. This only affects
characters in the range 0x80 through 0xa0.

Too many test cases were "miscellaneous".

Give objects descriptions and context so it is possible to issue
warnings instead of fatal errors for attempts to access objects of the
wrong type.

Sometimes it's an offset in an object stream or a content stream, so
file position is confusing in some cases.

As in other cases, this is to enable adding new member variables in
the future without breaking ABI compatibility.

Expose Pl_QPDFTokenizer, and have it do more of the work of managing
the token filter's pipeline.

Implement a TokenFilter class and refactor Pl_QPDFTokenizer to use a
TokenFilter class called ContentNormalizer. Pl_QPDFTokenizer is now a
general filter that passes data through a TokenFilter.

Adding a trailing newline in content normalization damages files whose
contents are split across streams in the middle of tokens. Let
QPDFWriter add the newline with the indicator to ignore the newline,
which it already does. This changes the way some qdf files look.

Remove a redundant method that was equal to another one with
additional arguments. This breaks binary compatibility, but there are
other ABI breaking changes in the upcoming release, so now is the time
to do it.