Use trakeva


The first commit does the code changes, it all compiles but the linking fails (I guess it was again an `ocp-build` broken assumption).

Then the second commit changes the whole build system to have something based on `oasis` (but, of course, the `_oasis` file is generated by a script).
(It took about 20 `push --force` to make Travis happy with the OSX backend, see the commit message for details).