Auto-detect whether delimiters codes should be handled as keys or char codes, which are different (see: http://unixpapa.com/js/key.html for an exhaustive discussion). This rolls back the 'delimiterKeys' API parameter committed yesterday.

Codes 45 (key = INSERT, char = -) and 46 (key = DELETE, char = .) are handled as chars.

Code 188 (, and < key) is intentionally not handled, and 44 (, char) should be used instead.