Add jumble solver plugin

[gaganchandan]

Add a new plugin called jumble which can be used to unscramble words. Source can be found in jumble.py in the plugins directory. No new dependencies are required.

[pnhofmann]

Hey, thanks! I like it.

Just small question, could you add a small comment about the words-file - like where this file is from and how it was generated. Basically both curiosity and maybe this information could be used to update the word-file someday?

Edit: same goes for the wordle plugin #1096 - which is even more interesting to update.