scripts/import_welt2000: update database instead of replacing everything
scripts/import_welt2000: update database instead of replacing everything

shadowoneau/skylines,TobiasLohner/SkyLines,Harry-R/skylines,kerel-fs/skylines,Harry-R/skylines,RBE-Avionik/skylines,kerel-fs/skylines,Harry-R/skylines,snip/skylines,RBE-Avionik/skylines,snip/skylines,Turbo87/skylines,RBE-Avionik/skylines,kerel-fs/skylines,Turbo87/skylines,skylines-project/skylines,Turbo87/skylines,shadowoneau/skylines,snip/skylines,TobiasLohner/SkyLines,shadowoneau/skylines,skylines-project/skylines,skylines-project/skylines,RBE-Avionik/skylines,Turbo87/skylines,Harry-R/skylines,TobiasLohner/SkyLines,skylines-project/skylines,shadowoneau/skylines