webmdshow: Build a common library of shared sources.

Because libraries are not a new invention, and compiling
the same common sources in all of our vcxproj's makes the
build unreasonably slow on underpowered machines (i.e.
laptops).

Add'l clean up:
- Fixed code generation, DLL to static runtime (MSVCRT -> LIBCMT)
  for projects (that have likely never previously been built in
  release mode).
- All projects with IDL files (and .c and .h files produced as
  IDL build outputs) have had their IDL files and products moved
  to an IDL group (aka filter aka folder).

Change-Id: I570ebe0df7cf2064965dcd1bdec67c650aade8ce