porting: gfanlib and gmp 4.0/4.1 (redhat)
fix: removed wrong assumes
chg: listvar(all) lists Top and Current instead of only Top
fix: handle undefined rings in ssi (from master)
fix: ssiReadRing for dummy rings
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