[z2257] Rewrite README as Markdown

* use Markdown syntax to allow github to display a formated README
* add new section "Further information" with links to various places
* move license to the end of the file to make things more readable
* add a note pointing to the COPYING file

(based on commit [12362] - c0e5c9d)

(based on commit [s1895] - 736a8da)