Adds GNU Robbo port

[btimofeev]

My first port of the beautiful old game.
Source code of port: https://github.com/btimofeev/GNU_Robbo_MiyooMini/

[XK9274]

Thanks for the pr!

Haven't looked at the files yet but, can you take a look over the licensing requirements on the source repos to see if we need to include any attribution to other devs/contributors or if there's any licensing restrictions on distributing any data files that may be bundled with it?

Hopefully I'll take a look at this PR this week and test it.

[btimofeev]

Haven't looked at the files yet but, can you take a look over the licensing requirements on the source repos to see if we need to include any attribution to other devs/contributors or if there's any licensing restrictions on distributing any data files that may be bundled with it?

The source code for the game is licensed under the GNU GPL version 2.
I have also included the gfx.h and gfx.c files from the Onion repository in order to rotate the image 180 degrees. As far as I am aware, these files are licensed under GNU GPL version 3.