Certain parametric constraints fail with kwmethod

[MasonProtter]

Sorry this isn't the cleanest example, but I couldn't boil it down any more. This errors:

julia> using KeywordDispatch

julia> @kwdispatch f(x::T) where {T}

julia> @kwmethod f(x::T; y::Type{TI}) where {T, TI <: Vector{T}} = y
ERROR: UndefVarError: TI not defined
Stacktrace:
 [1] top-level scope at /Users/mason/.julia/packages/KeywordDispatch/Hhjer/src/KeywordDispatch.jl:253

whereas it does not without the @kwmethod:

julia> f(x::T; y::Type{TI}) where {T, TI <: Vector{T}} = y
f (generic function with 1 method)

[simonbyrne]

I sort of fixed this in #9. Unfortunately it looks like you can't use Type{...} in signatures, I've opened a new issue (#10).