Apparently, this field was used to store light level of the
walkable area in pre-2.55 engines, prior to introduction of the
Regions.
In current engine, when loading games that old, this value is
copied into Regions for backwards compatibility.
While in newer games it actually stores "player character
view" override.
Renamed update_shadow_areas() into update_player_view(),
and tidied the code for clarity.
From upstream 71e7dc880b4496dd6937cec00a56f0de66137482
Leave it with a new name as `update_polled_stuff()` only in functions
related to the game update.
From upstream 95dc139f51e704da19792e5480e69bbfe7ec27aa
Walter Agazzi
Thierry Crozat
Paul Gilbert
Eugene Sandulenko
D G Turner