optimizations + bugfixes

* Bombs explode on damage/explosion
* Orbits spell fixed
* Performance: implemented shared component indexes,
compiled Lua caching, and updates only for changed projectile fields.
Also removed accumulating hidden entity slots.

src/app/inventory.h

@@ -153,6 +153,7 @@ public:
     void remove(int item) {
         const Loc l = where(item);
         take(item);
+        if (item && gun_.equipped() == item) gun_.equip(0);
         (void)l;
     }