Large set of changes to restore CiderPress build.

CiderPress and MDC now compile, and execute far enough to open
their respective "about" boxes, but I doubt they'll do much
more than that.

* Switch from MBCS to UNICODE APIs

Microsoft switched to UTF-16 (by way of UCS-2) a long time ago,
and the support for MBCS seems to be getting phased out.  So it's
time to switch to wide strings.

This is a bit awkward for CiderPress because it works with disk
and file archives with 8-bit filenames, and I want NufxLib and
DiskImgLib to continue to work on Linux (which has largely taken
the UTF-8 approach to Unicode).  The libraries will continue to
work with 8-bit filenames, with CiderPress/MDC doing the
conversion at the appropriate point.

There were a couple of places where strings from a structure
handed back by one of the libraries were used directly in the UI,
or vice-versa, which is a problem because we have nowhere to
store the result of the conversion.  These currently have fixed
place-holder "xyzzy" strings.

All UI strings are now wide.

Various format strings now use "%ls" and "%hs" to explicitly
specify wide and narrow.  This doesn't play well with gcc, so
only the Windows-specific parts use those.

* Various updates to vcxproj files

The project-file conversion had some cruft that is now largely
gone.  The build now has a common output directory for the EXEs
and libraries, avoiding the old post-build copy steps.

* Added zlib 1.2.8 and nufxlib 2.2.2 source snapshots

The old "prebuilts" directory is now gone.  The libraries are now
built as part of building the apps.

I added a minimal set of files for zlib, and a full set for nufxlib.
The Linux-specific nufxlib goodies are included for the benefit of
the Linux utilities, which are currently broken (don't build).

* Replace symbols used for include guards

Symbols with a leading "__" are reserved.