Made SWIG 3 a requirement when building the bindings
Made SWIG 3 a requirement when building the bindings

cellml/libcellml,cellml/libcellml,nickerso/libcellml,cellml/libcellml,nickerso/libcellml,MichaelClerx/libcellml,nickerso/libcellml,hsorby/libcellml,hsorby/libcellml,hsorby/libcellml,cellml/libcellml,MichaelClerx/libcellml,hsorby/libcellml,MichaelClerx/libcellml,nickerso/libcellml