RegioSQM 2.0.3 for Python 3.8

Adjust of the sequence of entries defined in the .svg written.

The sequence of the definition about items in the .svg affects their visual representation;
as if there were layers to consider here. The changes in the code base aim to re-establish
a pattern seen earlier in the version just forked from the Jensen group; ellipses put into
the background, behind the structure formulae. This feature got lost while working (and
altering) the code.

Simultaneously, this updates the documentation in the README.org, reintroduces a (now
again GitHub compatible) README.md and updates the documentation about the quick
test with 36 test molecules.