This change checks all paths in the ProjectSettings file for relativity and makes them relative to the location of the
ProjectSettings file if necessary. The paths are also correctly saved relative to the file.
The utility class FilePath wraps an instance of boost::filesystem::path. Using FilePath allows for easy comparision of
file paths on different platforms using absolute or relative paths. Whereever file paths are compared, this wrapper
should be used.
Eberhard Graether