fix docu string
simplify code in PrimaryDecomposition/RadicalDecomposition
declared and installed IsPrimeModule

as an attribute for modules
declared and installed SymmetricAlgebra
one ExteriorPower only works for IsFinitelyPresentedModuleRep
declared and installed ExteriorAlgebra
whitespace
declared and installed ExteriorPower
removed `obsolete' method for RadicalDecomposition

which was installed for IsFinitelyPresentedSubmoduleRep and
added RadicalDecomposition to intrinsic_attributes_specific_shared_with_factors_modulo_ideals