Added crude update ability to setup.exe

[Chris Faylor <cgf at cygnus dot com>]

I just made some changes to setup:

1) Store version information, gleaned from filenames in the registry.

2) Accept a "-u" option which will cause setup to run in "update mode", only
   downloading or installing newer versions of .tar.gz files.

3) Accept a list of packages to install on the command line.

If setup.exe detects that an attempt is being made to install to a
directory which seems to already have cygwin 1.1.0 in it, but there is
no version information in the registry, it will ask the user if it
should update the registry with default settings, appropriate for the
previous installation.

Anyway, what I'm aiming for is to be able to do something like this:

setup -u cygwin

And, for the most part, this works fine.  One problem I have is that,
right now, setup.exe uses HKLM to store the list of packages that have
been installed.  I guess I'll have to also use HKCU if the user can't
write to HKLM.

-- 
cgf@cygnus.com                        Cygnus Solutions, a Red Hat company
http://sourceware.cygnus.com/         http://www.redhat.com/