Wrap and compose functions

[frostney]

Allow to wrap and compose function

var self = this;
this.on('reset', function() {});
this.on('pause', function() {});

this.behavior('reset', function() { self.trigger('reset'); });
this.behavior('newgame', function() {
  self.trigger('reset'); 
  self.trigger('pause');
});

would become

this.on('reset', function() {});
this.on('pause', function() {});

this.behavior('reset', this.wrap(this.trigger, 'reset'));
this.behavior('newgame', this.compose([this.wrap(this.trigger, 'reset'), this.wrap(this.trigger, 'pause')]));