* slimmer stack frames in encoder
* fix MSAN problem in hasher_composite
(not dangerous, only in large_window mode)
* fix JNI decoder wrapper - power-of-two payloads fail to decode sometimes
* reformat polyfil.js and decode_test.js
* re-enable Js build/test
* improve decoder performance
* rewrite dictionary data in Java/Js to a shorter uncompressed form
* improve dictionary generation tool