Improves UI for Hints

I didn't really feel the need for the "hints" feature (except when I try to play in German, of course) but, since I added it, it might as well be somewhat easier and obvious to use, so I changed the multi-tap activation to a bog-standard icon.
Note that the limitations are still present and actually stricter: you can request the length any time you want, but you can only see the actual word *once* - and that disables the hint request completely for the duration of the game.

Furthermore, keep in mind that using the full word hint prevents you from sharing the replay key, and that the word itself will be highlighted in the results (if you actually play it as-is).