sci-astronomy/mosstack: New download url for mosstack. Added -r1-ebuild.

Package-Manager: portage-2.2.14
Merge pull request #1 from gentoo-science/master

Syncing my own fork. Sorry if I'm doing this wrong...
Syncing fork
Merge https://github.com/mickolaine/sci into mosstack
Merge pull request #306 from mickolaine/mosstack

Mosstack - updated ebuild because of download url