Migrate content out of opengl.org SDK area

[oddhack]

Many of these projects are years out of date or have broken links. Would like to migrate links into a curated page, probably in the Registry or Refpages area, take down the content, and redirect from opengl.org to the curated page. See

https://github.com/KhronosGroup/OpenGL-Refpages/wiki/Migration

for latest known status of SDK hosted projects / links.