Challenge skill increases, Siege Barrier fix

Some changes to the Challenge server:

• The light shafts have been modified to show approx thirty minutes before the central or perimeter spawns.
• The Spike Barrier is now notake and may only be created and finished on ground and hence not dropped in mid combat.
• Removed some impopular items from the central spawn.
• Rubble can no longer be bashed.
• New accounts start with 21 in all skills instead of 20 in order to allow for riding and wall bashing. The skill values of old accounts have been raised to 21 if they were lower.