Quarter/corner tiling

Not sure why the following issue wasn't duplicated to this github repo: https://bugs.launchpad.net/gala/+bug/1432067

> I'd like gala to support - in addition to tiling windows just to the left / right half of the screen when dragging per mouse - tiling to quarters of the screen. So, when dragging windows to some areas of the screen, the following should happen:
>
> - left top corner +/- some threshold --> tile window to the top left quarter of the screen
> - left center +/- some threshold --> tile window to the left half of the screen
> - left bottom corner +/- some threshold --> tile window to the bottom left quarter of the screen
> - right top corner +/- some threshold --> tile window to the top right quarter of the screen
> - right center +/- some threshold --> tile window to the right half of the screen
> - right bottom corner +/- some threshold --> tile window to the bottom right quarter of the screen
> - top of the screen --> maximize window
>
> This behaviour should - as already mentioned - be possible by dragging windows per MOUSE (so please no suggestions to keyboard control, THX!)
>
> Thank you in advance!
>
> best regards,
> Christian

I personally would also like keyboard support.

(I've been using Quicktile for quarter tiles in the mean time, but it has the following issue: https://github.com/elementary/gala/issues/104)
Update: Quicktile doesn't work in elementary OS Juno, see: https://github.com/ssokolow/quicktile/issues/95.