Fixed fake--em--dashes

[Grissess]

Tested briefly in a web browser, but beyond that not tested in practice; some verification would be nice, but it seems to work :)

The major fix is the (?:\s+|$) group after the ++ or ----the meaning of which is that "an operator must be followed by at least one whitespace character, or by the end of the message". It absorbed a previous "\s?" group used to separate the comment character (// or #) out. In practice, that means the following are legal:

• foo++ #being a bar
• <@blah>--
• But definitely whiz++ for being a bang

...the following, however, are not:

• But--as you can see...
• spang++whammo #thwonk

Suggestions welcome! :D

[imjoshdean]

Looks good! Thanks for the addition 👍