[1.6.0] Creeping Darkness blocks LOS for Feed

[jademonkey]

Creeping Darkness will block the LOS for Feed and prevent the talent from being used (or cancel an ongoing feed) while there is at least one tile of darkness between the player and the enemy, even when Dark Vision has been taken. This also affects the darkness tiles left by Dark Torrent, which means the attack will almost always cancel feed and prevent reapplication until there are no longer darkness tiles between the player and the target.