[merc2] Support texscroll, use in jak 1 in more places, fix envmap bug (#2303)

Three main changes:

- Adds support for the texture scrolling effect used on conveyor belts,
and turn it on for jak 2.
- Use merc instead of generic in jak 1 for ripple/water/texscroll stuff
(non-ocean water, lava, dark eco, etc). This is a pretty big speedup in
a lot of places.
- Fix a really old bug with blending mode used to draw environment maps.
The effect is that envmaps were half as bright as they should have been.

As usual, there's a flag to go back to the old behavior on jak 1. Set
these to `#t` to use generic like we used to.
```
*texscroll-force-generic*
*ripple-force-generic*
```

The format has changed, and everything must be rebuilt (C++, FR3's, GOAL
code)

common/custom_data/TFrag3Data.cpp

@@ -316,6 +316,7 @@ void MercModel::serialize(Serializer& ser) {
   ser.from_ptr(&max_bones);
   ser.from_ptr(&st_vif_add);
   ser.from_ptr(&xyz_scale);
+  ser.from_ptr(&st_magic);
 }
 
 void MercModelGroup::serialize(Serializer& ser) {