* bug - eval doesn't perform substitution on expression any more before 
  evaluating?  See the bug in bugdb_dev headers...
* <ifndef>
* <eval function="" />
this is a good idea; funcall via pointer is about 40 times faster than eval
(plus inevitable memory savings).  However many (most?) evals are caused by
"if expr".
* short form <eval/>
* limit size of file cache - also test efficacy.
** test on RedHat 9 showed no effect
Loading the same file repeatedly; the cache had no appreciable effect.
probably just uses extra memory.
