support board color change

[sugizo]

nice to have the parameter to change board color

e.g.
java -jar sgf2gif.jar -f ~/game.sgf -o ~/game.gif --board_color='brown'
or
whatever value, like in your code in classic theme
private val boardColor = Color.WHITE

thanks and best regards

[Kuhron]

I would also like this and can contribute a PR with this change if you like, @Ekenstein

[Ekenstein]

This'd only be applicable on the classic theme I suppose. The NES theme, which was the main idea for this project wouldn't really benefit from this.

But if someone is willing to add a PR for it, I might consider merging it 🙂

[ekbgab]

Consider also implementing your own theme if you wish to have another board color.