The rendering classes do not actually manage windows, and window was not
descriptive of what this class was doing. We decided that the class was
mostly analogous to what we call a "view" in ParaView.
This is required for installing the files. It is also useful for
developers because it adds the files to IDEs and creates test builds for
the header files. Those test builds highlighted some missing includes.
Specifically, I am trying to compile the code on OSX. OSX uses OpenGL
libraries in a different directory than most other installs (including
X11) and does not generally support GLX. These changes remove the files
that support GLX in systems that do not support it.
I also added several header files to the CMake lists that were not there
but should have been.
