Lot of bugfixes

* Adding clipper to generate the terrain's negative powder-contour offset.
* Fixing RDB issues (fracture, active trigger, performances)
* Fixing blood emission
* Fixing the freezing formula on liquids
* Fixing Steve spawning due to a missed test.
* Reaction table properly build

shaders/terrain.comp

@@ -16,6 +16,7 @@ layout(std430, set = 0, binding = 10) readonly buffer CellsOld { uint cells_old[
 layout(std430, set = 0, binding = 11) readonly buffer ExtOld { vec2 ext_old[]; };
 layout(std430, set = 0, binding = 52) readonly buffer BirthOld { uint birth_old[]; };   // the ages before the scroll
 
+layout(std430, set = 0, binding = 66) readonly buffer TerrainAgeOld { uint terrain_age_old[]; };
 layout(std430, set = 0, binding = 12) readonly buffer Scene { uint scene[]; };      // pixel scenes: 0 = none, else material + 1
 
 layout(std430, set = 0, binding = 18) readonly buffer Override { uint ovr[]; };    // cells restored from the persistent store (0xFFFFFFFF = none)
@@ -428,6 +429,7 @@ void main() {
     if (pc.shift_mode == 1) { // scrolling: reuse the simulated overlap, generate only the exposed strips
         ivec2 src = p + ivec2(pc.shift_x, pc.shift_y);
         if (src.x >= 0 && src.y >= 0 && src.x < pc.gw && src.y < pc.gh) {
+            terrain_age[i] = terrain_age_old[src.y * pc.gw + src.x];
             cells[i] = cells_old[src.y * pc.gw + src.x];
             ext[i] = ext_old[src.y * pc.gw + src.x];
             birth[i] = birth_old[src.y * pc.gw + src.x];   // a cell that stays keeps its age (0070d1e0: the age belongs to the cell)
@@ -435,6 +437,7 @@ void main() {
         }
     }
     birth[i] = birth_frame();
+    terrain_age[i] = 0u;
     if (ovr[i] != 0xFFFFFFFFu) {   // a cell that comes back from the store (only its word is kept): a burning cell or a flame gets the fade a new cell of its material has
         // (0070f450: the material's temperature_of_fire), so a fire that went out of the window goes on when it comes back instead of dying at its next update
         const uint oc = ovr[i];