Removes coremod (#3038)

From now on every integration must not rely on method stripping through
a coremod or @Optional. Notable example for a very good solution is IC2.

As consequence this drops all support for RF and mods must support on of
our supported energy types. At the time of writing, ForgeEnergy and
IC2/EU.

src/api/java/appeng/api/config/TunnelType.java

@@ -28,7 +28,6 @@ public enum TunnelType
 {
 	ME, // Network Tunnel
 	IC2_POWER, // EU Tunnel
-	RF_POWER, // RF Tunnel
 	FE_POWER, // Forge Energy tunnel
 	REDSTONE, // Redstone Tunnel
 	FLUID, // Fluid Tunnel

src/api/java/appeng/api/definitions/IParts.java

@@ -82,8 +82,6 @@ public interface IParts
 
 	IItemDefinition p2PTunnelEU();
 
-	IItemDefinition p2PTunnelRF();
-
 	IItemDefinition p2PTunnelFE();
 
 	IItemDefinition p2PTunnelLight();