this reverts 8676 (9c50d9e70314b0cd9eb0fe3bac8040d64a9965a5)
the new flag is from wdb-files so your database should be
already alright
also i've dropped the function Player::CanInteractWithNPCs
cause it was used only in one place and didn't seem to make anything
easier
NOTE for this flag:
it just means that the creature can be seen by ghost-players
too..
so they are still visible for alive players.. unless a special
aura or ther unitflag (spiritguide/healer) disables this..
(see next commit for it)
