[plt-scheme] uninstalling .plt packages in 299

> No need to delete.
> 
> setup-plt always re-builds the cache, for the collections it is running
> on. That is, if you pass no arguments to setup-plt, the whole cache is
> re-built. If you pass "-l ..." only some part of the cache is re-built.

Hm. I tried it without deleting the cache.ss file; I ran Setup PLT.exe, 
and it didn't overwrite the cache. Then starting up DrScheme gave an 
error that it couldn't find the collection and automatically exited.

Then I deleted cache.ss manually, reran Setup PLT.exe, and it didn't 
recreate the file, but it now starts up without the error.

Aha -- there's an ambiguity here. I'm talking about having installed a 
.plt file to my *user-local* library (~/Application Data/PLT 
Scheme/299.29/collects), and the cache file is in my *user-local* 
directory (~/Application Data/PLT 
Scheme/299.29/collects/info-domain/compiled/cache.ss). This is the file 
that isn't being updated automatically.

Dave