Add support of building GUI app for Apple macOS.

[Gubarev]

1. Include OpenGL in different way.
2. Link with OpenGL frameworks rather than libraries.

Public domain: yes

[akavel]

Thanks! I understand the original was not building, and now it just builds? or does it require something more?

Are you ok with releasing your modifications to public domain? If yes, can you please write this in the commit message? I need this to be able to safely merge this, I believe. Thanks!

[Gubarev]

now it just builds? or does it require something more?

Just builds :)
My configuration is latest default for development on Mac: macOS Sierra 10.12, Xcode 8.2.1 with command line tools.

Are you ok with releasing your modifications to public domain?

Yes

[akavel]

Please write your agreement to make it public domain in the git commit message, not in the github comment, ok? Thanks in advance!

[Gubarev]

How I can do this? As far as I know there is no direct way to edit message of pushed commit. Perhaps only suspicions actions which includes pushing with force.

[akavel]

Exactly - you need to locally do git amend, and then git push -f. This is normal way of doing such things, nothing suspicious in it! Or do you have some specific doubts with this? If so, maybe I can try to explain them.

You can also do this in a separate branch if you want - then you can make new commit (for example rebase or cherry-pick, then amend), then push the new branch and make new Pull Request instead of this one. But normally on GitHub you can amend commits (and push -f) to improve them based on review.