Fix support ref schemas as vector forms in a registry

[dvingo]

Addresses #847

Unwrap schemas in vector form for subsequent schema lookups.

[ikitommi]

This doesn't look correct:

(let [opts {:registry {:map (m/-map-schema)
                       :int (m/-int-schema)
                       ::test :map
                       ::test-2 [:map [:x :int]]}}]
  (m/schema [::test-2] opts)) ;=> :map

[ikitommi]

I don't think it should be ok to use the vector syntax in the first position (a schema type), e.g. this doesn't make much sense:

(let [opts {:registry {:map (m/-map-schema)
                       :int (m/-int-schema)
                       ::test :map
                       ::test-2 [:map [:x :int]]}}]
  (m/schema [::test-2 {:kikka "kukka"}] opts))

;; ... that would be:

[[:map [:x :int]] {:kikka "kukka"}]

[dvingo]

ahh, thanks for the feedback! I understand now and agree doing this will lead to other problems, I can use other strategies to get the behavior I want.