rewrote find-midi-device to take in either :in or :out to search for input or output midi devices (fixes issue with MPK Mini 2 where two devices are listed, one with input and one with output)
added missing change from previous commit
switched back to unchecked-inc instead of unchecked-inc-int as loop vars don't seem to allow int primitives...
work on benchmarks
rewored operators (sum, mul, sub, div) to use native java code, also improved operator macro for pure-clojure version