gource + its deps

[mxcl]

Closes #590
Closes #562

[what-the-diff]

PR Summary

• Added GLEW SourceForge site
  Included the site for the OpenGL Extension Wrangler Library
• Added GLM site
  Included the site for the OpenGL Mathematics Library
• Added Gource from GitHub
  Integrated Gource visualization tool from an unofficial source (acaudwell/Gource)

[jhheider]

Looks like this uses mesa-glu > mesa on linux with homebrew for OpenGL; mesa-glu just deps mesa, and mesa has a ton of deps, but they look like we've already packaged them.

[mxcl]

@jhheider not sure how you feel about this per-se, but I marked only glew as available darwin/aarch64 which means it is impossible for gource to build on anything but the same.

Really that restriction should fall through. I fear though that practically that's just a nightmare of complexity we can easily avoid by manually propogating the YAML. So I'll do that for now.

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Just being lazy, the failure for darwin/x86-64 looks tedious and pkging mesa looks tedious too, but don't want this work to go to waste.

[jhheider]

Agree back to front. Mesa will be a pain (looked into it in depth yesterday). Yes, we could dive through deps for platforms, but better to be explicit.

[mxcl]

needs brewkit 0.27.1 because we lost unzip somehow in the extract script