Add support for installing license files
This adds support for installing license files in install/share/licenses/project.
When adding a project, one can now list avaialable license files in the src and they will be installed in the above location. This also add the license files for each project and a selftest for licenses.
Not supported yet:
- Packaging from system stuff (eg Qt is packaged from system on Windows). Will not be supported.
- Plugin specific licenses. Will be suported.
Edited by Mathieu Westphal (Kitware)