docs: private String calculateProjectRelativeDirectory( VCProject vcProject ) throws MojoExecutionException
      {
          String relProjectDir = "";
          try
          {
              relProjectDir = getRelativeFile( vcProject.getBaseDirectory(), 
                      vcProject.getFile().getParentFile() ).getPath();
              if ( ".".equals( relProjectDir ) )
              {
                  relProjectDir = "";
              }
              else
              {
                  relProjectDir += "\\";
              }
          }
          catch ( IOException ioe )
          {
              throw new MojoExecutionException( ioe.getMessage(), ioe );
          }
          return relProjectDir;
      }