Add optional parent and position parameters to the display.newGroup()

[depilz]

With this you can create groups using display.newGroup([parent], [x, y])

[XeduR]

Given that the old/current optional parameters are undocumented and referred to as experimental, and as no one in Discord seemed to know about them, I think this change would be a fantastic change and a welcome addition.

[CLAassistant]

All committers have signed the CLA.

[depilz]

Any chance of accepting this some day?