introduce version code offset -1 for release candidates
introduce version code offset -1 for release candidates

kumy/cgeo,cgeo/cgeo,cgeo/cgeo,rsudev/c-geo-opensource,Bananeweizen/cgeo,pstorch/cgeo,SammysHP/cgeo,mucek4/cgeo,Bananeweizen/cgeo,matej116/cgeo,superspindel/cgeo,kumy/cgeo,SammysHP/cgeo,S-Bartfast/cgeo,matej116/cgeo,SammysHP/cgeo,rsudev/c-geo-opensource,cgeo/cgeo,mucek4/cgeo,superspindel/cgeo,kumy/cgeo,superspindel/cgeo,samueltardieu/cgeo,rsudev/c-geo-opensource,matej116/cgeo,samueltardieu/cgeo,tobiasge/cgeo,auricgoldfinger/cgeo,pstorch/cgeo,S-Bartfast/cgeo,mucek4/cgeo,tobiasge/cgeo,pstorch/cgeo,cgeo/cgeo,tobiasge/cgeo,auricgoldfinger/cgeo,S-Bartfast/cgeo,auricgoldfinger/cgeo,samueltardieu/cgeo,Bananeweizen/cgeo