hypermap Combinatorial oriented hypermaps
 H=hypermap(sigma,alpha) creates a hypermap from two permutations
 that satisfy <sigma,alpha> transitive
 
 as an example of possible input we give a small hypermap from a
 square-octagon tesselation of the plane (i.e. this is a hypergraph
 embedded on the torus)
 sigma=perm({[1 24 20],[2 14 9],[3 11 13],[4 18 23],[5 21 17],[6 7 10],[8 16 12],[15 19 22]});
 alpha=perm({[1 2 3],[4 5 6],[7 8 9],[10 11 12],[13 14 15],[16 17 18],[19 20 21],[22,23,24]});
 H=hypermap(sigma,alpha);
 
 hypermap Properties:
    sigma - the permutation representing vertices
    alpha - the permutation representing edges
    alphaInverseSigma - the permutation representing faces
    n - the number of darts
 
 hypermap Methods:
    hypermap - constructs a hypermap from two permutations
    genus - computes the genus of the hypermap
    showVertices - prints the vertices of the hypermap to screen
    showEdges - prints the edges of the hypermap to screen
    showFaces - prints the faces of the hypermap to screen
    dual - creates the combinatorial dual of the hypermap
    boundaryFaceToDartModEdge - computes the matrix representing \partial_2
    boundaryDartModEdgeToVertex - computes the matrix representing \partial_1
    classicalBoundaryFaceToDart - computes the matrix representing \overline{d}_2
    classicalBoundaryDartToVertexPlusEdge - computes the matrix representing \overline{d}_1