Make Board Flippable

[Dumuzy]

I love this software! And I like to do sets of puzzles with a flipped board from time to time. So as to maybe better learn what the opponent is threatening me. I would therefore like to have a little checkbox which makes the board flip around. This should be on the main page. And maybe it should be remembered for the next time I open the program. Just for consistency, when all the other stuff is remembered.

[brianch]

I had never thought about doing puzzles looking from the opponent's perspective to be honest, perhaps it would be a nice idea for my practice sessions too hehe

It's not difficult to add but I'm not 100% sure yet on how to put this option on the interface, I'll think a bit about it, seems like a good feature to have indeed.