[due diligence] std.xml

[Justin Johansson]

This module should be removed altogether from Phobos forthwith.

The code was obviously submitted and accepted without peer
review, either that or the peers were idiots as well.

It would be better to say that Phobos does not have an
XML library yet, and to seek submissions, rather than
maintain this piece of codswallop in the latest distribution.

Let's not even talk of deprecation.  Any D user currently
using std.xml is completely misguided.

Justin