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/apply.comp

@@ -19,6 +19,8 @@ void main() {
     uint cs = cells[i], ct = cells[t];
     vec2 et = ext[t];
     if ((it.x >> 31) != 0u) cs ^= DIR_BIT;               // gas bounced: flip horizontal direction
+    terrain_age[t] = (cell_mat(cs) << 16) | 0x100u;
+    terrain_age[i] = (cell_mat(ct) << 16) | 0x100u;
     cells[t] = cs;
     ext[t] = vec2(uintBitsToFloat(it.z), uintBitsToFloat(it.w));
     cells[i] = ct;