patch: updated windows build documentation

[Dave Cottlehuber]

This patch updates the Windows build docs, to note newer versions of
dependencies that work, & also how to compile with the free Microsoft
Visual Studio 2008 C++ Express compiler.

- using latest VS2008 compiler & SDKs
- converting wxWidgets to compile with newer MS tools and via command
line instead of GUI
- latest tested version of OpenSSL + wxWidgets

# On branch improved_INSTALL-W32.md
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#       modified:   INSTALL-WIN32.md

git fetch git://github.com/dch/otp.git improved_INSTALL-W32.md

cheers,
Dave