minor typo
updated ReducedBasisOfModule.g
installed Zero, One, and MinusOne for IsHomalgLibSingularRingRep

+ added entries Zero, One, and MinusOne
  to CommonHomalgTableForLibSingularTools

this commit should (partially) become obsolete
added GAPHomalg.g? to use SingularForHomalg in an external GAP

(needs RingsForHomalg v2013.01.08 and libsing 0.2)

Report: Purity.g works with assertion level 6