In the wiki, this was a separate page. I don't think this split is useful,
since the information about what is stable and what not seems randomly split
between the two pages.
Links are adjusted for our own pages. Some external links to gentoo and other
projects seem to be broken, but it's a chore to fix them.
Instead of saying that patches for portability are not accepted, say that this
is decided case-by-case. This is what happens in practice, and we tend to
discuss each patch on its own merits.
Some sentences are reworded a bit where they sound awkward.