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/hit_liquid_channels.glsl

@@ -0,0 +1,15 @@
+// 00ab8f10: one hit-liquid event per positive damage channel, in native order.
+void projectile_hit_liquid(int k, float projectile, int tb, vec4 adds, float scale, vec2 hit, vec2 impulse, uint seed) {
+    const Ent v = ents[k];
+    const vec4 a = ftf(tb + 12), b = ftf(tb + 13), c = ftf(tb + 14);
+    const float channel[13] = float[13](projectile * v.ex9.x, (a.y + adds.x) * v.ex12.x,
+        c.w * v.ex9.y, a.z * v.ex9.z, a.x * v.ex9.w, b.y * v.ex12.y,
+        b.x * v.ex12.z, (a.w + adds.y) * v.ex12.w, c.x * v.ex13.x,
+        b.z * v.ex13.z, b.w * v.ex13.w, c.y * v.ex14.y, c.z * v.ex14.z);
+    const vec2 factors = bloodProjectile[tb / TYPE_STRIDE].xy;
+    const int fx = (fti(tb + 11).y >> 4) & 15;
+    for (int i = 0; i < 13; ++i) {
+        if (i == 8) continue; // Healing is a negative damage channel.
+        hit_liquid(k, channel[i] * scale, hit, impulse, factors.x, factors.y, fx, hash3(seed, uint(i), 411u));
+    }
+}