[CM] Snd 19.6

[bil at ccrma.Stanford.EDU]

Snd 19.6:

s7: added tools directory (timing tests etc)
     moved most-positive|negative-fixnum to *s7*
     s7_load now parallels scheme load;
       it returns NULL if file not found (or a directory).
     added s7_call_with_catch and define-expansion*.

checked: sbcl 1.5.4|5

Thanks!: Kjetil Matheussen, Woody Douglas