:not humanizer

[frenchy64]

This seems like a cheap and easy trick to automatically get a :not humanizer for most (simple) schemas.

Before supporting negated composite schemas we need to enhance humanizing to distinguish between conjunctions and disjunctions. Then we can leverage this for explaining negations:

;; should be [:and "should be a string" "should be a symbol"]
(me/humanize (m/explain [:and :string :symbol] nil))
;=> ["should be a string" "should be a symbol"]

;; should be [:or "should be a string" "should be a symbol"]
(me/humanize (m/explain [:or :string :symbol] nil))
;=> ["should be a string" "should be a symbol"]

[ikitommi]

that's clever. Great tests!