Major refactor part 1.

src/constants.nvgt

@@ -235,3 +235,8 @@ const int FALL_DAMAGE_MAX = 4;
 const int RESIDENT_SLING_COOLDOWN = 4000;  // 4 seconds between shots
 const int RESIDENT_COLLECTION_CHANCE = 10; // 10% chance per basket per hour
 
+// Utility functions
+int abs(int value) {
+    return value < 0 ? -value : value;
+}
+