update charmatrix2d to use rows/cols isntead of x/y internally, for clarity
update charmatrix2d to use rows/cols isntead of x/y internally, for clarity

fernandobrito/parrot-linear-algebra,fernandobrito/parrot-linear-algebra,Whiteknight/parrot-linear-algebra,fernandobrito/parrot-linear-algebra,Whiteknight/parrot-linear-algebra,fernandobrito/parrot-linear-algebra