Fix #9295

Deprecate `push!(a, k, v)` in favor of `push!(a, k=>v)` because the old
signature was inconsistent with the varargs version of `push!` to add
multiple elements to a collection.

TODO: Add tests

Conflicts:
	base/deprecated.jl

Author: ivarne

base/deprecated.jl

@@ -276,3 +276,6 @@ const base64 = base64encode
 
 @deprecate map!(f::Callable, dest::StridedArray, A::StridedArray, B::Number) broadcast!(f, dest, A, B)
 @deprecate map!(f::Callable, dest::StridedArray, A::Number, B::StridedArray) broadcast!(f, dest, A, B)
+
+#9295
+@deprecate push!(t::Associative, key, v)  setindex!(t, v, key)

base/dict.jl

@@ -246,7 +246,7 @@ end
 getindex(t::Associative, k1, k2, ks...) = getindex(t, tuple(k1,k2,ks...))
 setindex!(t::Associative, v, k1, k2, ks...) = setindex!(t, v, tuple(k1,k2,ks...))
 
-push!(t::Associative, key, v) = setindex!(t, v, key)
+push!(t::Associative, p::Pair) = setindex!(t, p.second, p.first)
 
 # hashing objects by identity