Mass: make Weapon copyable.

This is necessary to add weapon copying.

src/Mass/Mass.h

@@ -101,6 +101,42 @@ struct WeaponPart {
 };
 
 struct Weapon {
+    Weapon() = default;
+
+    Weapon(const Weapon& other) {
+        name = other.name;
+        type = other.type;
+        parts = Containers::Array<WeaponPart>{other.parts.size()};
+        for(UnsignedInt i = 0; i < parts.size(); i++) {
+            parts[i] = other.parts[i];
+        }
+        customStyles = other.customStyles;
+        attached = other.attached;
+        damageType = other.damageType;
+        dualWield = other.dualWield;
+        effectColourMode = other.effectColourMode;
+        effectColour = other.effectColour;
+    }
+    Weapon& operator=(const Weapon& other) {
+        name = other.name;
+        type = other.type;
+        parts = Containers::Array<WeaponPart>{other.parts.size()};
+        for(UnsignedInt i = 0; i < parts.size(); i++) {
+            parts[i] = other.parts[i];
+        }
+        customStyles = other.customStyles;
+        attached = other.attached;
+        damageType = other.damageType;
+        dualWield = other.dualWield;
+        effectColourMode = other.effectColourMode;
+        effectColour = other.effectColour;
+
+        return *this;
+    }
+
+    Weapon(Weapon&& other) = default;
+    Weapon& operator=(Weapon&& other) = default;
+
     std::string name;
     std::string type;
     Containers::Array<WeaponPart> parts;