UnramDeg3 for GAP 4

See

UnramDeg3-2019.09.26.pdf or
http://mathweb.sc.niigata-u.ac.jp/~hoshi/Algorithm/UnramDeg3/UnramDeg3-2019.09.26.pdf or
https://www.math.kyoto-u.ac.jp/~yamasaki/Algorithm/UnramDeg3/UnramDeg3-2019.09.26.pdf

See the following for further explanations:

H3nr.pdf or
http://mathweb.sc.niigata-u.ac.jp/~hoshi/Algorithm/UnramDeg3/H3nr.html or
https://www.math.kyoto-u.ac.jp/~yamasaki/Algorithm/UnramDeg3/H3nr.html