minimal constructor for GroupRing with no initialisation

src/GroupRings.jl

@@ -102,22 +102,8 @@ function GroupRingElem{T<:Number}(c::AbstractVector{T}, RG::GroupRing)
    return GroupRingElem{T}(c, RG)
 end
 
-function GroupRing(G::Group, pm::Array{Int,2})
-   size(pm,1) == size(pm,2) || throw("pm must be square, got $(size(pm))")
-   RG = GroupRing(G, initialise=false)
-   RG.pm = pm
-   return RG
-end
-
-function GroupRing(G::Group, basis::Vector)
-   basis_dict = reverse_dict(basis)
-   pm = try
-      create_pm(basis, basis_dict)
-   catch err
-      isa(err, KeyError) && throw("Products are not supported on basis")
-      throw(err)
-   end
-   return GroupRing(G, basis, basis_dict, pm)
+function GroupRing(G::Group; init::Bool=false)
+   return GroupRing(G, collect(elements(G)), init=init)
 end
 
 function GroupRing(G::Group, basis::Vector, pm::Array{Int,2})