Repairable errors in extensions' XML break the game

[Arkhist]

When an error in the XML of an extension occurs, in current PF, the game crashes.

1. Such errors should never cause a crash.

When such an error does not prevent the game from launching (wrongly typed IRC message)

2. Pathfinder should tell the (user/extension developer) a list of errors it encountered (all? a selection?), unless the extension specifies to not show errors.

3. If none of the errors are fatal, Pathfinder should allow the user to continue through to play the extension if they so desire.

Commit ed19e4a "fixed" such an error by hiding it, this should not be done.