Create "make stable release" script

This can be done along with the next release and automates all the steps. With the script releasing becomes easy and it is a defined procedure.

Things to carry out:

• merge current master to stable (there should be no merge conflicts!)
• git-tag the new stable release with the new version (how to set?)
• publish builds (using the workers) on vadere.org as a stable release
  • carried out by the continuous deployment with the corresponding tag