This mode is based very heavily upon the javascript mode.

Make character bindings work for maps that define a nofallthrough.

(Though it looks rather dead.)

Signed-off-by: Jan Keromnes <janx@linux.com>

Issue #459

Typing a self-closing tag in XML mode would cause it to fire, so you'd
end up with something like <foo><bar/foo> when you typed the slash.