Assemble methode doesn't support traingle mesh with udin=2

[bboeyken]

The assemble function can't deal with triangulized surface in udim = 2 for lagrange and nedelec interpolation. assemble calls quaddata and _allocate_workspace. This last method calls the following function, for a lagrange reference space:

BEAST.jl/src/bases/local/laglocal.jl

Lines 213 to 214 in 55ec0a3

	# Evaluete linear lagrange elements on a triangle
	function (f::LagrangeRefSpace{T,1,3})(t) where T

This methode calculates the normal of a triangle. However in a udim = 2, a triangle has no normal vector.

A solution is to overload this function so that it doesn't require the normal vector.

Example for the issue is the following:

Ω = meshrectangle(1.0, 1.0, 0.5, 2)
X = lagrangec0d1(Ω, boundary(Ω))

I = BEAST.Identity()
assemble(I, X,X)

Which give rise to "BoundsError: attempt to access Tuple{} at index [1]", meaning there is no normal vector.