[merc2] Support texscroll, use in jak 1 in more places, fix envmap bug

[water111]

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)

[ManDude]

merc doesn't render dark eco properly:

generic: