License update

[Zefk]

I was not sure how to phrase the credits, so I did not pull request this, but Challener (Redshrike) needs to be credited for mods of his tiles and tiles parts I used as textures. I want to ensure Challener (Redshrike) is credited.

Something like this I suppose:

tilesets/castle.tiles.png
Christopho, adapted from Challener (Redshrike): http://opengameart.org/content/16x16-indoor-rpg-tileset-the-baseline and mods from those tiles made by Zane Kukta.

tilesets/desert.tiles.png
Zane Kukta. some tiles textured with Challener (Redshrike) tiles: http://opengameart.org/content/16x16-indoor-rpg-tileset-the-baseline

tilesets/forest.tiles.png
Zane Kukta, some tiles textured with Challener (Redshrike) tiles: http://opengameart.org/content/16x16-indoor-rpg-tileset-the-baseline

I honestly do not care if I am credited for the graphics unrelated to others. For instance, the switch graphics or chests I made. No need to credit me for those unless you guys really want to. Those are CC0.