Enable robots to check their energy level.

src/main/java/li/cil/oc2/common/entity/RobotEntity.java

@@ -868,6 +868,16 @@ public final class RobotEntity extends Entity implements Robot {
             return actionProcessor.rotate(direction);
         }
 
+        @Callback(synchronize = false)
+        public int getCurrentEnergy() {
+            return energy.getEnergyStored();
+        }
+
+        @Callback(synchronize = false)
+        public int getMaxEnergy() {
+            return energy.getMaxEnergyStored();
+        }
+
         @Callback(synchronize = false)
         public int getLastActionId() {
             return actionProcessor.lastActionId;