v0.8.9

General improvements

• added swap-vals! and reset-vals! functions (from Clojure 1.9)
• added new functions to standard library: joker.http/send, joker.os/mkdir, joker.os/cwd, joker.os/ls, joker.base64/encode-string, joker.math/sin, joker.math/cos, joker.math/hypot, joker.math/pi (a var).
• made ExInfo (return by ex-info) a map with :message, :cause, and :data keys.