onStart is not called on individual tweens.

[cainmartin]

When creating an individual tween, all callbacks work, with the exception of the onStart.

var obj = { x: 0 };
var testTina = new TINA.Tween(obj, ['x'])
    .to({ x: 10 }, 200) 
    .onStart(function () {
        console.log('Starting');
    })
    .onUpdate(function () {
        console.log(obj.x);
    })
    .onComplete(function() {
        console.log('Completed');
    })
    .start();

Given the above code - 'Starting' is never output to the console.
However, it is possible to get onStart to fire by placing the tween in a timeline.

var timeline = TINA.Timeline();
var obj = { x: 0 };
var testTina = new TINA.Tween(obj, ['x'])
    .to({ x: 10 }, 200) 
    .onStart(function () {
        console.log('Starting');
    });
    timeline.add(testTina, 0);     
    timeline.start();

It is likely this occurs because an individual tween is appears to never be added to the list of _inactivePlayables. A cursory glance suggests that it is only when a tween is removed from the _inactivePlayables list and set to active that the onStart callbacks are fired.

It should be possible to add a fix the Playable.start method to also fire the onStart method.