Improved international keyboard support in demos
The playable demos have a bad UX on non-EN keyboard layouts.
Please add a few alternative keys, e.g., for Watris:

* Add **C** as more universal "hard drop" key (Z is always a bad choice as an action button, e.g., for DE and FR layouts, where it is not next to X).
* **ArrowUp** as "spin" key and **ArrowDown** as "hard drop" key, to allow full one handed control on any keyboard (and making it playable for one-handed people).

And, I guess there are also other smart choices for the other demos, for good UX worldwide, and for one handed control.
