Add a order property to LinearPDESystemOperator (#58)
* Add a degree property to LinearPDESystemOperator
* degree -> order
* LinearPDESystemOperator.degree -> order in tests
Co-authored-by: Andreas Klöckner <inform@tiker.net>
* Add a degree property to LinearPDESystemOperator
* degree -> order
* LinearPDESystemOperator.degree -> order in tests
Co-authored-by: Andreas Klöckner <inform@tiker.net>