Remove the build time generation of config.h and xmlversion.h.

Remove the build time generation of config.h and xmlversion.h.

This adds a bat file which will generate config.h and xmlversion.h
into the win32 directory.  I updated include paths and everything
seems to build.

[Peter Kasting, 2009-01-14 23:15:29]

Tony and I chatted some over IM about this.

The main goal of this change is to increase build speed.  By eliminating a few
files on disk VS has to dependency-check, Tony estimates this change could save
50-100 ms on a build (at least, on the first build after restarting VS, when it
has to re-stat the disk).  Neither of us have measured actual changes.

The tradeoff is that whenever we change libxml, we need to remember to run this
batch file to regenerate things manually.

Personally, I don't think we should do this.  I think the estimated time savings
are immaterial but the chance of goofing something up on a later library upgrade
is nonzero, and in principle autogenerated files just feel better to me than
pregenerated ones.  However, if someone else feels strongly that we should do
this and/or that I've missed a big win, please chime in.

(Side note: on Linux/Mac right now, you apparently need to manually generate
these already, since SCons doesn't autobuild them the way Windows does.  I think
we should fix this.)

[tony, 2009-01-14 23:53:39]

Adding darin and dean who may have comments.