lib/Base.js
function(evname, callback, context) {
    this._events = this._events || {};
    var a = this._events[evname] = this._events[evname] || [];
    a.push({
      cb: callback,
      ctxt: context || this
    });
    return this;
  }
function(evname, callback, context) {
    this._events = this._events || {};
    var a = this._events[evname] = this._events[evname] || [];
    a.push({
      cb: callback,
      ctxt: context || this
    });
    return this;
  }
function ( evname , callback , context ) { this . _events = this . _events || { } ; var a = this . _events [ evname ] = this . _events [ evname ] || [ ] ; a . push ( { cb : callback , ctxt : context || this } ) ; return this ; }
Bind event listener

@param {string} name of event
@param {function} callback if event is triggered
@param {object} context in which callback is called
@return {this}
Bind event listener