Check enable flag in compose pane too

When writing an email with the add-on disabled, it would still apply fixes
to the HTML entered. This change fixes that so that disabling the add-on
via its pref also disables fix-ups in the compose pane.
Replace multiple wingding chars in a span with smileys too

When you type :):) in Outlook it places both smileys in the same block of
Wingdings text. This situation was not contemplated before, so fix it by
checking and replacing each character in the span.
Add bomb symbol replacement
Bump version number to 1.3, TB max to 17