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18. Cat-1-groups

### 18. Cat-1-groups

`AutomorphismGroupAsCatOneGroup(G)` Inputs a group G and returns the Cat-1-group C corresponding th the crossed module G-> Aut(G).
`HomotopyGroup(C,n)` Inputs a cat-1-group C and an integer n. It returns the nth homotopy group of C.
`HomotopyModule(C,2)` Inputs a cat-1-group C and an integer n=2. It returns the second homotopy group of C as a G-module (i.e. abelian G-outer group) where G is the fundamental group of C.
`ModuleAsCatOneGroup(G,alpha,M)` Inputs a group G, an abelian group M and a homomorphism alpha: G-> Aut(M). It returns the Cat-1-group C corresponding th the zero crossed module 0: M-> G.
`MooreComplex(C)` Inputs a cat-1-group C and returns its Moore complex [M_1 -> M_0] as a list whose single entry is a homomorphism of groups.
`NormalSubgroupAsCatOneGroup(G,N)` Inputs a group G with normal subgroup N. It returns the Cat-1-group C corresponding th the inclusion crossed module N-> G.

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