Fixes bug in BlockOperatorBasicTest
runTest for kind=1 was erroneously using P2ConstantLaplaceOperator instead of P2ConstantVectorLaplaceOperator for the (0,0) block. This led to a memory problem when calling P2Function::isDummy(), and, unfortunately, did not necessarily crash. Additionally commit adds a reminder that the second invocation of runTest is actually unclean, since we work with a P2P1TaylorHoodBlockFunction, but should use a P1P1StokesBlockFunction.