Polynomial roots with Jenkins-Traub algorithm

Find polynomial roots with Jenkins-Traub algorithm.

Find polynomial roots with Jenkins–Traub algorithm. The mex-function is using the CPOLY algorithm from ACM Algorithm 419 for polynomials with complex coefficients, and the RPOLY algorithm from ACM Algorithm 493 for polynomials with real coefficients. The algorithm calculates all of the zeros of a polynomial whose coefficients are the elements of a vector in order of decreasing powers. Leading zeros in the coefficients are discarded.