More artifact power use descriptions

Updates power use descriptions for zone specific world-artifacts, boss, quest, and special artifacts.

Updated handling of weapon special effects to pass the special effect field to the object code (facilitates handling multiple effects within object definitions).

Blighted Maul's on hit shockwave will not hit the primary target.

Wintertide's winter storm graphic will expand in size to match its effect. Updated the icestorm particles effect to accept radius and density parameters (this might benefit from some more tweaking).

Reduced the number of mental effects the Wintertide Phial will remove.

The Crystal Focus can now be applied to shields (updates the special_combat fields appropriately).

Prox's Lucky Halfling Foot benefits from Charm Mastery.

Penitence cures a more reasonable (fewer) number of diseases.

Updated the DAMAGE_SHIELD definition to note damage reflection in its tooltip and show shield strength in it's icon.

Awakened Staff of Absorption gets a special damage message and death message for the player if he manages to kill himself with it. Drain damage is based on maximum life (buff).