add support keyboard controls

[sleep-walker]

When running this application on machines with keyboard and mouse (typically attached to "TV"), it is uncomfortable to use mouse drag&drop actions for every move.

Would that be possible to add also keyboard controls? (Left/Right/Up/Down)

Thanks in advance.

PS: I really appreciate this project and your work on this. Thanks for what you already done. <3

[GfEW]

More than 5 years in, was about to make the same suggestion, although for two other, additional reasons:

1. Keyboard controls are a matter of accessibility. Not everyone can coordinate and perform so many touch-slides wery well, be it due to hardware issues or personal inabilities. Given the proper means though (usually involving some kind of keyboard device), 2048 can be a very interesting game to play - and win!

2. Even on mobile devices, sliding games like 2048 can be played much more fluently and, to speed enthusiasts, more enjoyably, on an external keyboard. With touch-swipes, the 1000ish moves required for a plain 2048 win (let alone higher numbers) are hard to get done in less than 15 min due to the sheer, physical interaction, whilst on a keyboard (e. g. online at https://2048.neiunderscore.com/), 5 min are easily within reach.

These reasons couldn't be more different, but for both, being able to control privacy friendly 2048 with the arrow keys would be a big improvement.