Allow programatic save

[pehrlich]

For example, I would like to have it save before unload the page every time, so that I can rapidly debug changes without having to save and resume settings manually.

Unfortunately, the following code doesn't work:

window.onbeforeunload = ->
  gui.save()

It gives the error:

Uncaught TypeError: Cannot read property 'selectedIndex' of undefined dat.gui.js:2854
markPresetModified dat.gui.js:2854
dat.GUI.dat.gui.GUI.common.extend.save dat.gui.js:2261
window.onbeforeunload

[stellatigre]

This issue still occurs in the latest build - this functionality can be invoked by firing the fake click event on the save button:

function saveDatGUI() {
    dat.dom.dom.fakeEvent($('.cr .button')[0], 'click');
}

but that feels hacky. This functionality would be useful in writing tests which involve a datgui component.
If it's deemed not an issue, perhaps close this ?