[CM] Snd 21.7

[bil at ccrma.Stanford.EDU]

Snd 21.7

s7: added (*s7* 'muffle-warnings?) and s7_output_string
     bool s7_flush_output_port (was void)

checked: notcurses 2.3.13, sbcl 2.1.8
   notcurses 2.3.17 behaves very strangely in row 0, so I've covered row 
0
   with a header box.  It's probably some new notcurses configuration 
option.

Thanks!:  Brad Christensen, Woody Douglass, JGM, Anders Vinjar