OpenSystemsDevelopment / qpdf

Fix comment, remove restriction that doesn't actually matter.

If the stream isn't filterable but we call getStreamData, throw a
regular exception instead of a logic error so that normal error
handling and reporting mechanisms will be used.

Initial implementation provided by Casey Rojas <crojas@infotechfl.com>
Some problems are fixed in a subsequent commit.

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.

Tweak the message so that we inform the user that we are mitigating
data loss.

Avoid calling jpeg_mem_src and jpeg_mem_dest. The custom destination
manager writes to the pipeline in smaller chunks to avoid having the
whole image in memory at once. The source manager works directly with
the Buffer object. Using customer managers avoids use of memory source
and destination managers, which are not present in older versions of
libjpeg still in use by some Linux distributions.

The latter catches underflow/overflow.

Now that the test suite runs clean with address sanitizer, add some
test cases that previously were used to expose memory errors.

There was a missing free causing a memory leak in some test code. The
memory leak was not in library code.

Resolve link error on cygwin