make install target is incomplete

[infinity0]

Currently make install only installs headers and shared libraries (when giving -DCPP-NETLIB_BUILD_SHARED_LIBS=On to cmake). It ought to install documentation, other metadata (e.g. authors/license) and anything else too.

(This is a requirement for getting the package into Debian proper.)

[infinity0]

On top of the issue I just referenced, a final remaining task (for the 0.10 branch) is to have cmake build/install the existing sphinx docs into ${CMAKE_INSTALL_DOCDIR}.

I recommend installing libs/network/doc/_build/html as ${CMAKE_INSTALL_DOCDIR}/html/network, then when the MIME docs are done, they can be installed as ${CMAKE_INSTALL_DOCDIR}/html/mime.

But first cmake needs to integrate with the Makefile for sphinx - I'm not sure of the best way to do that.