* contrib improvement: the SB-SIMPLE-STREAMS contrib now defines
STRING-SIMPLE-STREAM and FILE-SIMPLE-STREAM as subclasses of
STRING-STREAM and FILE-STREAM, respectively.
+ * a more robust x86-64 disassembler. (thanks to Lutz Euler)
* fixed some bugs revealed by Paul Dietz' test suite:
** MISC.564: defined out-of-line version of %ATAN2 on x86.