more user‐friendly handling of chat commands

• make the split more forgiving in the "report" chat command (https://github.com/Charcoal-SE/SmokeDetector/pull/10755): change urls = argsraw[0].split(' ') to urls = argsraw[0].split(sep=None)
• !!/reject 12345 5 false positives, no known hits.; account for \d+ (19+ characters)
• maybe make exceptions for < 19 chars if: 'superseded by \d+' or match('author') && match('request')
• for watches, allow leading whitespace (if that's the only problem)
• addblu -- allow a trailing comment (throw away the comment?)