1.0.23.37: more CLOS and classoid thread safety

1.0.23.37: more CLOS and classoid thread safety

 * Rename *BIG-COMPILER-LOCK* as *WORLD-LOCK*.

 * Use it to protect classoids, layouts/wrappers, obsolete instance
   updating, etc.

 * Rename sevaral functions which assume their callers are holding the
   lock to have % prefix. Perhaps we should have a separate prefix
   convention for "requires called to lock"? Or a nifty macro layer?
   (Actually there are probably places where read/write locks (or
   STM!)  would be a win...)

 * ENSURE-CLASS-USING-CLASS needs to set up type translations only
   while PCL is being build.

 * DEFCLASS and ENSURE-CLASS-USING-CLASS are now expected to be thread
   safe.

 * Test-case for parallel defclass and make-instance.