Mana curse/shield patch version 3

  This patch is ready to be aplied to Vanilla angband 2.9.5-alpha

  The mana shield flag works as in the previous versions but the
mana curse is now dependant on the pval of the item, using the following
table :
        pval    mana curse
        <=-5    100%
         -4      70%
         -3      50%
         -2      30%
         -1      20%
          0      10%
          1      20%
          2      30%
          3      50%
          4      70%
        >=5     100%

  So, if you wield a mana cursed item with pval of 2. For every 100 points
of damage you suffer you will loose 20 sp also (or 1sp every 5 damage).
  Mana curse is not cumulative, it will be used the item with worse mana
curse

Still to do :
Display mana curse and mana shield at appropiate wizard commands.

Luthien
josedura@wanadoo.es