Generator: replaced `mOrder` with `mProcessed` in GeneratorEquationImpl (WIP).
Generator: replaced `mOrder` with `mProcessed` in GeneratorEquationImpl (WIP).

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