additional commands inserted in libminmaxgd:

odot -- dual multiplication of two monomials, polynomials, series, or smatrices

odotstar -- dual Kleene star of a square smatrix

duallfrac -- dual left residual of two smatrices with the corresponding dimensions (I think I didn't enter any check if the dimensions of the two matrices are ok or not...)

prcauspm -- causal projection of transfer matrices, i.e., elements in prcauspm(A) may have negative exponents in gamma but all exponents in delta are non-negative!
