since all the python bindings are required for building the doc, extract
them into admin/doc-pybind.txt.
because the pybind python extensions require Cython python module to build,
we have to move them into another requirement file, and install them after
Cython is installed.
Signed-off-by: Kefu Chai <kchai@redhat.com>
RTD does not support installing system packages, the only ways to install
dependencies are setuptools and pip. while ditaa is a tool written in
Java. so we need to find a native python tool allowing us to render ditaa
images. plantweb is able to the web service for rendering the ditaa
diagram. so let's use it as a fallback if "ditaa" is not around.
also start a new line after the directive, otherwise planweb server will
return 500 at seeing the diagram.
Signed-off-by: Kefu Chai <kchai@redhat.com>