Lots of cleanup things.

Added the bitmaps back, and added the wizard style program group
selection dialog.

Got rid of references to backup etc. inserted by the installer wizard
-- we don't use these.

Got rid of conditionals for Windows 3.1, ditto.

Changed version to 1.6a2.

Changed default install directory to "C:\Python16" (not really, but close).

Install only one copy of python16.lib.

Install the two MS DLLs (versioned) and python16.dll (unversioned) in
the system directory.

Install Tcl/Tk and expat in the DLLs directory.