[CM] Snd 24.3

[bil at ccrma.Stanford.EDU]

Snd 24.3:

s7: format now always returns a string (where it used to return #f it
     now returns "")
sam.c: bugfixes and improvements thanks to David Jaffe

checked: sbcl 2.4.3

Thanks!: Michael Edwards, Norman Gray, David Jaffe