[plt-scheme] dynamic libraries installer

> Is the installer for the dynamic libraries really necessary? 

In a cosmic sense, no; life would continue without it. :-)
The reason an installer is helpful for those libraries is 
because the system directory varies among Windows versions.
If we produced, say, a .ZIP file, people would have to find 
the system directory and copy the files there.  That's 
error-prone.

The installer creates a Start menu entry, but does not otherwise 
modify the Registry.

-- Paul