-/* Return overlay of world map wherein all cell positions visible from player's
- * positions have flag VISIBLE set.
- *
- * This is achieved by spiraling out clock-wise from the player position,
- * flagging cells as VISIBLE unless they're already marked as HIDDEN, and, on
- * running into obstacles for view that are not HIDDEN, casting shadows from
- * these, i.e. drawing cells as HIDDEN that would be hidden by said obstacle,
- * before continuing the original spiraling path.
- *
- * Shadowcasting during spiraling is initially lazy, flagging only the shadows'
- * interior cells as HIDDEN and their border cells as HIDE_LATER. Only at the
- * end are all cells flagged HIDE_LATER flagged as HIDDEN. This is to handle
- * cases where obstacles to view sit right at the border of pre-estabilshed
- * shadows, therefore might be ignored if HIDDEN and not cast shadows on their
- * own that may slightly extend beyond the pre-established shadows they border.
+/* Update "t"'s .mem_map memory with what's in its current FOV, remove from its
+ * .t_mem all memorized things in FOV and add inanimate things in FOV to it.