OpenSystemsDevelopment / qpdf

Use "QPDF" only for the QPDF class itself.

External libraries for Windows are now built automatically in the
qpdf/external-libs repository and include openssl in addition to zlib
and jpeg. Use these, and update the Windows build to build with the
openssl crypto provider by default. We leave the native crypto
provider enabled in case there is a problem with openssl and also to
continue to exercise that code.

Hopefully this is it.

Most of the README files have been renamed. Refer to the new names.