nail gun rework

damage immunity graphic is more obvious
difficulty mode no longer increases after killing final boss (it was too confusing)

tech: Higgs mechanism - you can't move when firing, reduce harm by 60% when firing
  removed Galilean group

removed gun flechettes
removed critical bifrication
removed railroad ties
removed incendiary (for nail gun)

nail gun:
  needle gun: accurate, piercing mobs, fire 3 at a time
  rivet gun: accurate, ballistic arc, doesn't use much ammo
    tech: bigger rivets (9x stack)
  all nails
    radioactive 2s tick (about 70% damage increase)
      0.5s full tick
      4s longer tick
    critical hits -> explosion (from flechettes)

js/mob.js

@@ -164,16 +164,16 @@ const mobs = {
                             time: simulation.drawTime
                         });
                     }
-                    if (true) {
-                        //check for nearby mobs
+                    // if (true) {
+                    //     //check for nearby mobs
 
-                    }
+                    // }
                 },
                 endEffect() {},
                 dmg: tickDamage,
                 type: "dot",
                 endCycle: simulation.cycle + cycles,
-                startCycle: simulation.cycle
+                startCycle: simulation.cycle + 29 //makes sure it doesn't tick on first application
             })
         }
     },