[Bug-gnubg] Windows Installation routine

[Ian Shaw]

The Windows installation routine (020930) fails if setup.exe is placed in the 
directory you are installing to, e.g. in your existing c:\gnubg.
The "directory already exists" message doesn't appear and there are lots of 
errors writing over the existing dlls.
If you "Ignore" the errors, gnubg won't start up, reporting that it can't find 
a dll, even though it exists.