amberc.js: call amberc.main() with arguments

now amberc can be run with
  var amberc = new AmberC();
  amberc.main();
where it processes commandline parameters.

Or it can be run with
  var amberc = new AmberC();
  amberc.main(['-m', 'MainClass', 'MainClass.st', 'output']);
amberc: move old amberc to amberc.sh
amberc: new executable based on amberc.js
amberc.js: update usage() output