Fixes problem for non-zero rhs and Jacobi smoothing for P2 operator
The problem resulted from an indexing issue in the function p2::macroface::smoothJacobiEdgeDoF(). When the rhs array was accessed it got passed indices computed with edgedof::stencilIndexFromHorizontalEdge() instead of edgedof::macroface::indexFromHorizontalEdge() same for the other two types of edges. This commit fixes this.