Discussion of blanks and void handling

See http://chat.stackoverflow.com/transcript/message/37259990#37260398 and also https://github.com/metaeducation/ren-c/issues/518, and https://trello.com/c/9sOtDYcS/86-failed-conditionals-like-if-false-or-while-false-return-no-value-at-all-instead-of-none