Unit tests for dimensionality checks refactored. Initial skelton implementation of unit checks begun.
Unit tests for dimensionality checks refactored. Initial skelton implementation of unit checks begun.

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