cmake 3.1

[Michael Dickens]

FYI that I created a unified patch to bring the CMake port to 3.1.2 from
the current SVN head, and attached it to the appropraite ticket <
https://trac.macports.org/ticket/46493#comment:12 >. I think this change
keeps the same functionality with the Darwin Platform changes as before;
the CMake devs spread this into 2 files now. I also am proposing to add
myself as a co-maintainer; I use CMake a -lot-, and keep up with its
development -- so, I'm in a good position for testing and updating. I
would appreciate any feedback on testing both the actual build (does the
cmake port build/upgrade?) as well as functionality (does it work with
your CMake-based projects?). - MLD