[Feature request] Pangram analyzer

[mooomooo]

Sometimes the grids are (single/double/triple/...) pangrams, so having a count / histogram of letters currently filled in could help identify missing letters to help with the remaining clues.

[yourealwaysbe]

I don't really get much time to implement things unless i'm really motivated, so i probably won't get around to this myself anytime soon. Pull requests welcome :)

It might be possible to fit this in neatly in the ClueTabs widget. At the moment this just shows clue lists, and is used both on the main screen and the clue list screen. If doing so, i would split out the ClueTabs pages into fragments, and possibly allow some configuration of which tabs are shown for a particular usage of the widget.