Test Stokes Identities (#108)
* add tests for stokes identities * fix docs for h_min Co-authored-by: Andreas Klöckner <inform@tiker.net> * clean up relative error in test_stokes Co-authored-by: Andreas Klöckner <inform@tiker.net>
* add tests for stokes identities * fix docs for h_min Co-authored-by: Andreas Klöckner <inform@tiker.net> * clean up relative error in test_stokes Co-authored-by: Andreas Klöckner <inform@tiker.net>