[CM] Snd 20.9

[bil at ccrma.Stanford.EDU]

Snd 20.9:

Snd: clm.rb and snd-test.rb updated for Ruby 3.0, thanks to Mike.

s7: added s7_load_c_string and s7_load_c_string_with_environment
     tools/tmock.scm, tnum.scm, concordance.scm
     notcurses_s7.c assumes version 2 of notcurses; for version 1, pass 
-DNOTCURSES_1=1.

checked: Fedora 33, Ubuntu 20.10, sbcl 2.0.10

Thanks!:  Woody Douglass, Christos Vagias, Mike Scholz, IOhannes m 
zmoelnig,
           David Runge