[CM] Snd 25.5

[bil at ccrma.Stanford.EDU]

Snd 25.5:

s7: added (*s7* 'hash-table-missing-key-value), default=#f
           (*s7* 'iterator-at-end-value), default=#<eof>
     changed s7.h s7_closure* to s7_lambda* (old forms are still 
available)

checked: sbcl 2.5.5

Thanks!:  johnm, Norman Gray