index variables in LOOP
* optimization: faster floating-point SQRT on x86-64
* bug fix: more accurate ROOM results on GENCGC platforms
+ * fixed bug #233.b: make constraint propagation notice when a variable
+ value is changed after it is referenced but before it is used
* fixed some bugs revealed by Paul Dietz' test suite:
** DOCUMENTATION returns NIL instead of "" for method combinations
that don't have a docstring