implement brush cost gauges

they're a little ugly at the moment, and can be a little useless for most simple brushes, but whatever we'll make them better later

static/online-users.js

@@ -89,6 +89,19 @@ export class User {
             return false;
         }
     }
+
+    getStats(wallInfo) {
+        return {
+            astSize: this.haku.astSize,
+            astSizeMax: wallInfo.hakuLimits.ast_capacity,
+            numRefs: this.haku.numRefs,
+            numRefsMax: wallInfo.hakuLimits.ref_capacity,
+            fuel: wallInfo.hakuLimits.fuel - this.haku.remainingFuel,
+            fuelMax: wallInfo.hakuLimits.fuel,
+            memory: wallInfo.hakuLimits.memory - this.haku.remainingMemory,
+            memoryMax: wallInfo.hakuLimits.memory,
+        };
+    }
 }
 
 export class OnlineUsers extends EventTarget {