Add a LICENSE file

[jhermann]

Hi, "… are released under an open source license" means you need to state what that license is. ;)

One of the Creative Commons ones would be the obvious choice.

[danielhickman]

I agree, but it should also include the separate ones that are "discovered elsewhere"

[lewisnyman]

This will become problematic if each icon discovered elsewhere has different licenses. Some licenses forbid you to re-license them under somewhere else. I think it would be easier just to keep the individual licenses for each group of icons?

[deadbaed]

or maybe just license all the icons under the same license, clean and simple

[jhermann]

A first step would be to solve the easy case and clearly license "native" contributions, Then you can still think about the other cases.

[simonv3]

@bnvk Any preference of license for the things already here?