[Bug] MeshSlicer module not working with DelaunayMesh

[emmanuellfc]

Describe the bug
The module MeshSlicer does not work with meshes creating using DelaunayMesh

To Reproduce
A minimal code that reproduces the error:

import delaunay
import meshtools 
import plot 
import meshslice 

var pts = [ Matrix([0,0,0]),
            Matrix([1,0,0]),
            Matrix([0,1,0]),
            Matrix([0,0,1]) ]
var m = DelaunayMesh(pts)

for (g in 0..m.maxgrade()) print m.count(g)

var slice = MeshSlicer(m)
var sc = slice.slice(Matrix([0.5,0,0]), Matrix([1,0,0]))

Show(plotmesh(sc, grade=0))

Expected behavior
The last line should return a plot of the slice, but instead it returns the follwowing error:
Error 'NotAnInst': Can only invoke methods on objects.

[softmattertheory]

Thanks so much for reporting this @emmanuellfc! I'll get to work on trying to fix the issue.