This allows one to configure how a subsequent reset will behave and also trigger a reset. Fixes #350 and fixes #173
cpx build compiles and loads and works in repl; test suite not run yet esp8266 not tested yet
Also, rename Direction.IN to Direction.INPUT and Direction.OUT to Direction.OUTPUT. This simplifies using them. Prior to the nativeio split this would have led to clutter in the top-level namespace but having digitalio prevents this. Fixes #152