Toucan 1.15.0

• defmodel now uses Potemkin's defrecord+ to define corresponding record types rather than clojure.core/defrecord. This macro works similarly to vanilla defrecord but does not redefine the class if the body of the defrecord form has not changed since its initial definition. This fixes many annoyances in REPL-based development where reloading a namespace defining a Toucan model would require reloading any namespaces that referred to the resulting class directly, e.g. for class-based dispatch in interfaces, protocols, or multimethods. (#69)