0.01  2017-08-08
       Start on initial version
 0.02  2017-08-08 - 2017-09-02
       Improve POD
         - Typos
         - Add head1 for Source Code
       A grid minimally consists of one vertical and one
       horizontal line
       Adding tracks returns also the newly created line.
       $track->area($line_from, $line_to);
       Makefile.PL
        - She bang
        - chmod 755
       t/01-load.t: isa_ok();
       Use MANIFEST.SKIP rather than ignore.txt