Adding license file with incomplete list of artists.

The information was collected by Alige.
Update license file with EJlol as author of the orange item.
License file: fix directory name of tileset graphics.
Adding summon flowers. Icon created by Korcha, edited by v0id.

Thanks to v0id for helping with the dye strings.
TODO: add to license file.
Adding rose hat created by Nami, skipy and Alige.
Change item id's of summon flowers and rose hat, since 891 is already taken.
Temporary definitions of evil woodland monsters.
Add bluepar sprite made by meway based on the pinkie.

TODO: add this also to license file.