fix: mistake when given single row matrix

commit 21e5498945046a644d94b783c0fafe2cfbd8be89 in master
fix: memory leak while calling gcd with a term and a non-term poly
new: division and gcd of integer polynomials via factory

added conversion functions between integer polynomials in Singular and Factory
extended the singclap_gcd and singclap_pdivide functions to cover the case where
ground ring is integer
chg: moved all routines for tropical geometry to tropical.cc/.h