Adding two tests for compound units.
Adding two tests for compound units.

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