[Add] Rumble the screen a little if you take armour damage.

TODO

@@ -20,7 +20,6 @@ Major:
   -- Missile smoke.
   -- Engine glow -> need models.
   -- More special effects.
-  -- Have some kind of screen shaking for afterburner and friends.
   -- Cloaking effects?
   -- Maybe some fancy displacement effects for some ships.
   -- More outfits.

src/pilot.c

@@ -254,6 +254,10 @@ void pilot_hit(Pilot* p, const Solid* w, const unsigned int shooter,
   else if(p->armour-damage_armour > 0.) {
     p->armour -= damage_armour;
     dam_mod = damage_armour/p->armour_max;
+
+    // Shake us up a bit.
+    if(p->id == PLAYER_ID)
+      spfx_shake(dam_mod*100.);
   }
   else {
     // We are officially dead.