move SIBYLL stuff from Framework/Cascade to where it belongs

sibyll2.3c.f into ThirdParty and the rest of SIBYLL-related code into Processes/Sibyll

created branch 83-move-sibyll-stuff-from-framework-cascade-to-where-it-belongs

mentioned in merge request !30 (merged)

closed via merge request !30 (merged)

mentioned in commit a888bf32

mentioned in issue #86 (closed)