No (d|th)readed Tclkit builds

For the record: I've decided not to provide / maintain threaded  
builds of Tclkit.

No big news, because the current Tclkit download page did not contain  
threaded builds until now anyway.  But I did at some point intend to  
switch over to threaded builds for 8.5 - no longer.

My reasons are:
- don't want to manage two release collections (not just tclkits,  
also the extensions)
- don't think it's needed, multi-tasking suits me fine, also for  
multi-core use
- don't think threads will be solid enough across all software  
involved for a long time

If you want threads anyway, you'll either have to build things  
yourself using a modified genkit, or the new kitgen which can build  
threaded Tclkit Lite's.  Or alternately, have a look at the various  
options offered by ActiveState.

Then again, I *will* support Metakit in threaded mode for those souls  
who depend on it (MK's -shared flag can be useful as inter-thread  
data exchange, even for in-memory databases).  So if you run into any  
problems with MK, whether in threaded mode or otherwise, please do  
let me know.  My main development machine is dual-core and 64-bit, so  
I can definitely test and debug such cases.

This applies to the open source side of things.  Contact me if you  
need other fee-based arrangements.

-jcw