switched to OpenCV, #13.
open & save operations, #11.
updated deps.
removed deprecated curry dep.
operation class & ported decode operation.
ported encode operation.
auto auto, the JavaScripter in me...
RIBS_GETTER utility macro, #15.
removed  & simplified operation api, #14.
resize operation, #7.
wrap native image object, #16.
use of NanDisposePersistent.
partially simplified operation api, #21.
test formula computation & added curry dep (again yeah).
enhanced resize tests.
first impl.
`computeAnchor` & tests (needed for crop).
`computeRegionOrigin`, tests and `computeAnchor` factorization.
normalize png compression, #20.
crop operation, #8.