visual studio compatibility

[Joe Buck]

[ reverse engineering msvc ]

> Object layout we can't do anyway. They've patented most of it (You can
> therefore find most of it documented in the patents), and as they
> get more desperate to stop open source software, i'd think we don't want
> to be anywhere near the cross-hairs.

It might be possible to do a partial job without violating their patents;
there's nothing special in the case of single inheritance.  But yes, any
implementation that is fully binary compatible with MSVC has to violate
a patent.