Investigate screen reader access for minefield

[freaktechnik]

Currently the minefield is plain broken when looked at with a screen reader. The screen reader sees the value of the cell without it being "uncovered". One possible solution is to add the value only as soon as the cell is uncovered. Further all cells with a mine need a label, saying that they contain a mine, and not nine.

[freaktechnik]

Just setting the aria-label to a fitting value would probably be sufficient. Since in most cases screenreaders then don't actually read out the contents of the element.

[freaktechnik]

https://developer.mozilla.org/en-US/docs/Web/Accessibility/Mobile_accessibility_checklist

[freaktechnik]

Output cursor coordinates, so user knows where he is in the field?

[freaktechnik]

Can I savely convert aria-labels in gaia-headers to titles?

[freaktechnik]

The only thing I'm not complying with the checklist is hiding text in cells with color: transparent and not having any other means of indicating its hidden state.

[freaktechnik]

The windows narrator doesn't announce the cell state, but I guess I set the aria attribute for them so that should be fine.