Add is_zero(::NCRing) as an alias of is_trivial (Nemocas#1991)

Author: emikelsons

src/Rings.jl

@@ -212,6 +212,27 @@ rings are also called zero rings.
 """
 is_trivial(R::NCRing) = !is_domain_type(elem_type(R)) && iszero(one(R))
 
+@doc raw"""
+    is_zero(R::NCRing)
+
+Test whether the ring $R$ is trivial. However, the recommended method
+for doing this is [`is_trivial`](@ref).
+
+```jldoctest
+julia> R, (x,) = polynomial_ring(QQ, [:x]);
+
+julia> S=quo(R,1)[1]
+Residue ring of R modulo 1
+
+julia> is_trivial(S)
+true
+
+julia> is_zero(S)
+true
+```
+"""
+is_zero(R::NCRing) = is_trivial(R)
+
 @doc raw"""
     is_perfect(F::Field)