Weaponised powers, cursed changing items & fixes

[DameryDad]

• Allow re-usable (-1) powers to be weaponised in the same way that other spells and powers are.
• For spells & powers stored on items with a casting level, set the MU- and PR- casting levels to the stored level as well as the overall casting level.
• Extend "changing" items to allow cursed types.
• Define the store: attribute for bag-type objects which can be used with "nostore" to define a bag from which can be taken from but not stored.
• Extend GM's add-items dialog to cater for equipment.
• Fixed spell-storing items displaying "ghost" spells.
• Fixed issue with removing memorised spells.