ArBaseControls should be an abstract class?

[kalwalt]

ArBaseControls in the original repository: https://github.com/AR-js-org/AR.js/blob/master/three.js/src/threex/threex-arbasecontrols.js#L1-L38 See this two lines of code:

//////////////////////////////////////////////////////////////////////////////
//      Functions
//////////////////////////////////////////////////////////////////////////////
/**
 * error catching function for update()
 */
ArBaseControls.prototype.update = function () {
  console.assert(false, "you need to implement your own update");
};

/**
 * error catching function for name()
 */
ArBaseControls.prototype.name = function () {
  console.assert(false, "you need to implement your own .name()");
  return "Not yet implemented - name()";
};

https://github.com/AR-js-org/AR.js/blob/be7c9083df5a651c2ab978ddd7c1a33409c4d40b/three.js/src/threex/threex-arbasecontrols.js#L26-L36 This suggest me that ArBaseControls should be an abstract class and these two methods virtual to be implemented in ArMarkerControls.

[kalwalt]

This was done in PR #12