[haXe] swhx, haxe and neko version compatibility

[Nicolas Cannasse]

> Hi Nicolas,
> When neko and haxe versions change SWHX compatibility gets broken,
> understandably. Let's keep the swhx compatible version links below the
> new versions and put a disclaimer maybe. This is all IMHO. :))

In the future, things should be a lot more stable for SWHX. This is
because we started resolving new problems in SWHX than some things were
added directly into haXe/Neko. This will simplify and stabilize SWHX
once it's adapted to haXe 1.08.

In general, I'm thinking twice before breaking backward compatibility,
and most of the haXe API are very stable. Only the most recently added
ones are still subject to refactoring or package changes depending on
evolutions of the standard library.

Nicolas