add RF API and add concept of energy usage to machines + controllers

src/main/java/cofh/api/energy/IEnergyReceiver.java

@@ -0,0 +1,38 @@
+package cofh.api.energy;
+
+import net.minecraftforge.common.util.ForgeDirection;
+
+/**
+ * Implement this interface on Tile Entities which should receive energy, generally storing it in one or more internal {@link IEnergyStorage} objects.
+ * <p>
+ * A reference implementation is provided {@link TileEnergyHandler}.
+ *
+ * @author King Lemming
+ *
+ */
+public interface IEnergyReceiver extends IEnergyConnection {
+
+	/**
+	 * Add energy to an IEnergyReceiver, internal distribution is left entirely to the IEnergyReceiver.
+	 *
+	 * @param from
+	 *            Orientation the energy is received from.
+	 * @param maxReceive
+	 *            Maximum amount of energy to receive.
+	 * @param simulate
+	 *            If TRUE, the charge will only be simulated.
+	 * @return Amount of energy that was (or would have been, if simulated) received.
+	 */
+	int receiveEnergy(ForgeDirection from, int maxReceive, boolean simulate);
+
+	/**
+	 * Returns the amount of energy currently stored.
+	 */
+	int getEnergyStored(ForgeDirection from);
+
+	/**
+	 * Returns the maximum amount of energy that can be stored.
+	 */
+	int getMaxEnergyStored(ForgeDirection from);
+
+}