Add full block wired modems

These act similarly to conventional wired modems, but with the advantage
that they are a full block. This means they can be attached to
peripherals which are not solid (such as chests). Further more, as they
do not have a direction, they allow wrapping peripherals on all 6 sides.

It's worth noting that wired modems do not require a cable - they will
automatically form connections to adjacent network elements when placed.

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -47,6 +47,7 @@ import dan200.computercraft.shared.network.ComputerCraftPacket;
 import dan200.computercraft.shared.network.PacketHandler;
 import dan200.computercraft.shared.peripheral.common.BlockCable;
 import dan200.computercraft.shared.peripheral.common.BlockPeripheral;
+import dan200.computercraft.shared.peripheral.common.BlockWiredModemFull;
 import dan200.computercraft.shared.peripheral.diskdrive.TileDiskDrive;
 import dan200.computercraft.shared.peripheral.modem.BlockAdvancedModem;
 import dan200.computercraft.shared.peripheral.modem.WirelessNetwork;
@@ -180,6 +181,7 @@ public class ComputerCraft
         public static BlockTurtle turtleAdvanced;
         public static BlockCommandComputer commandComputer;
         public static BlockAdvancedModem advancedModem;
+        public static BlockWiredModemFull wiredModemFull;
     }
 
     public static class Items