Fix NullReferenceException at getCapacity->getBlockMetadata (#97)

* fix NullReferenceException on getBlockMetadata

* oh no-no, please be static, it's your present! :)

src/main/java/crazypants/enderio/machine/solar/SolarPanelNetwork.java

@@ -99,7 +99,7 @@ public class SolarPanelNetwork {
     private static int getCapacity(TileEntitySolarPanel panel, int panelsCount) {
         int capacity = ENERGY_PER;
 
-        if (panel != null) {
+        if (panel != null && panel.hasWorldObj()) {
             int meta = panel.getBlockMetadata();
             switch (meta) {
                 case 0: // Default