Adapt zip_gallery plugin to @saimn recommendations
Adapt zip_gallery plugin to @saimn recommendations

* One single entry point for the 'zip' property

saimn/sigal,xouillet/sigal,t-animal/sigal,jasuarez/sigal,saimn/sigal,t-animal/sigal,saimn/sigal,t-animal/sigal,jasuarez/sigal,xouillet/sigal,xouillet/sigal,jasuarez/sigal