fix #6793 handling of scheme relative image urls
fix #6793 handling of scheme relative image urls

Bananeweizen/cgeo,tobiasge/cgeo,pstorch/cgeo,tobiasge/cgeo,auricgoldfinger/cgeo,matej116/cgeo,Bananeweizen/cgeo,cgeo/cgeo,cgeo/cgeo,rsudev/c-geo-opensource,Bananeweizen/cgeo,pstorch/cgeo,rsudev/c-geo-opensource,auricgoldfinger/cgeo,tobiasge/cgeo,matej116/cgeo,cgeo/cgeo,auricgoldfinger/cgeo,S-Bartfast/cgeo,S-Bartfast/cgeo,matej116/cgeo,rsudev/c-geo-opensource,cgeo/cgeo,pstorch/cgeo,S-Bartfast/cgeo