Increases performance of EquivalenceChecker and adds string constructor for the matrices.
Removes unneeded templates from the multiply, submatrix and enlarge methods and moves method implementation into the class file.
Trying to speed up the equivalence checking. When large matrices (e.g. 10x10) it is not really possible to create a copy of every permutation matrix (for 10x10 there are 3.6 million of them)
Got equivalence checker to work with no huge array of permutations or any matrix multiplications at all.
Fixes problem with computing the hash of an EquivQuiverMatrix when created from string. Although the compute_hash() matrix is now protected and virtual calling it in the IntMatrix constructor does not mean that the EquiQuiverMatrix version is used.
Adds underlying graph class which is wrapper around IntMatrix with a convenient constructor to get the matrix for the undirected graph underlying a quiver