Add licenses for this project (closes #49)

[YtvwlD]

As @vitasomething suggested in #49, this project should have a license.

This PR adds not one license, but two:

The code (that is, the entire repository, except for the data/worlds/chaosdorf folder) is licensed under the GNU General Public License, version 3.

The world (that is, the data/world/chaosdorf folder) is licensed under Creative Commons Attribution Share Alike, version 4.

But, as you probably know, relicensing requires consent from everyone who made a contribution.

So, please add a comment containing:

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

Feel free to unsubscribe from notifications for this issue afterwards. :)

contributors

• @dodonator
• @YtvwlD
• @vitasomething
• @hwmrocker
• @inktrap
• @xenonhexafluorid
• @s22tthom
• @svhoy
• @gulyash
• @jopejoe1
• @alphonus
• @narco2z
• @Artin01

[YtvwlD]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[Artin01]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[hwmrocker]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[jopejoe1]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[svhoy]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[vitasomething]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[YtvwlD]

bump @dodonator @inktrap @xenonhexafluorid @s22tthom @gulyash @alphonus @narco2z

[gulyash]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.

[xenonhexafluorid]

I license past and future contributions to the code under the GPLv3 license.
I license past and future contributions to the world under CC-by-SA 4.0.