-Mountable mobs/borgs/taurs can now let the rider in control without requiring a riding crop.
-And yes, riding crop has always been "the key" for rider control for these mechanics.
-Also tweaks the AO a little bit more because ouch my ocd.
-Taller icons no longer sink into the tile below on the resize mechanics.
-Living mobs now have a var (vis_height) for their icon height, and humanmob species have a new var (icon_height) that overrides the vis_height for the resize proc.
-Also earlyports some tweaks to ambient occlusion. The new filter system took the old filter's settings as "make the shadows megathick and dummy intense" and that was ugly.
-Fixes several instances of runtime spam caused by lack of sanity checks in nifsoft procs.
-Fixes a runtime spam caused by 512>513 transition having renamed a fake ao filter argument.
-This also fixes the fake ao.
Ports an item stack that can be used to mark trails, useful for explorers, miners, and anyone else who doesn't want to get lost or wants to make the room more colorful.
The previous client-side optimization made lighting overlays go fully
opaque when it was dark, making it so species darksight didn't let you see
anything. This fixes that by making a dark_soft icon state that has
opacity matching the LIGHTING_SOFT_THRESHOLD.
