LOOP accepts logic/none, infinite or no loop
LOOP accepts logic/none, infinite or no loop

This gives two new ways to specify to LOOP not to loop at all (NONE!
and FALSE), and a way to tell it to loop infinitely (TRUE).

Numbers <= 0 continue to mean "don't loop".

codebybrett/ren-c,rgchris/ren-c,hostilefork/rebol,giuliolunati/ren-c,draegtun/ren-c,rgchris/ren-c,draegtun/ren-c,giuliolunati/ren-c,rgchris/ren-c,codebybrett/ren-c,draegtun/ren-c,kealist/ren-c,kealist/ren-c,kealist/ren-c,rgchris/ren-c,draegtun/ren-c,rgchris/ren-c,codebybrett/ren-c,kealist/ren-c,hostilefork/rebol,codebybrett/ren-c,draegtun/ren-c,giuliolunati/ren-c,kealist/ren-c,draegtun/ren-c,hostilefork/rebol,hostilefork/rebol,codebybrett/ren-c,hostilefork/rebol,codebybrett/ren-c,kealist/ren-c,giuliolunati/ren-c,hostilefork/rebol,giuliolunati/ren-c