This makes it possible for other plugins to force allow placing of shops
and avoid potential issues in the check if multiple plugins are changing
the allow settings.
ALso while the allow counters were a nice idea they might not have even
worked correctly because in the case of only one plugin disallowing it
they would've still returned true at the end. Only if one listener
allowed it and another disallowed it the end result would be disallow.
This also makes the BuildPermissionEvent implement Cancellable (which is
an inverted allowed) in order to easily ignore events that are already
disallowed by another listener.
Phoenix616
Phoenix616