Implement webpage to track progress on classes and compliance with API

[gcasa]

Per our discussion in November, @hmelder came up with the idea of creating a webpage to track this information. Per that conversation it would:

1. Track existing headers
2. Track Cocoa headers
3. Compare the two to determine how compliant we are with the current API

I am adding this here so that we have a place to track it. Please feel free to add a new repo to do this.

[ivucica]

@dszidi Why did this get closed without discussion?

[dszidi]

Apologies. To my knowledge, this site was archived up until very recently where Greg opened it up again. I asked him if the existing issues could be closed and was given the go-ahead.

@gcasa should we reinstate the recently closed issues?

[gcasa]

Any issues in gnustep.github.io repository should be moved.

[gcasa]

I think this one is relevant to any of the new work being done. Leave it open.

[dszidi]

@gcasa Sounds good.
@ivucica sorry for any confusion

[ethanc8]

I will probably try to get objc-diff working; I think I got it working a couple of years ago but I will want to use a newer fork of ObjectDoc, newer LLVM version, and make sure it actually works.