Refactored the BaseActionSource (#3063)

* Refactored the BaseActionSource

It now uses an interface `IActionSource` instead of a concrete class and further
subclasses. 

Instead of relying on a specific class for a certain action type, it now
uses methods with Optional as return values to determine a player or
machine issuing an action. Refer to the JavaDocs for the exact behaviour.

* `IActionHost` no longer extends `IGridHost`

It never used the additional functionality and if needed the `IGridNode`
will also provide a reference to the corresponding `IGridHost`.

Due to most crafting related GUIs being hardcoded to `IGridHost`, 
they no longer work when `IActionHost` is not extending it. Actually
`IActionHost` is the better solution for it, as it prevents us from looking
the grid up via the `IGridHost` and potentially finding a wrong grid.

* Interfaces now only lock the currently worked slot.

This allows `DualityInterface#onChangeInventory` to update slots of the same interface, should they be the source for a requested item and therefore updating their working set accordingly to queue further crafting requests for unfulfilled stack requirements.

src/main/java/appeng/me/helpers/MachineSource.java

@@ -0,0 +1,58 @@
+/*
+ * This file is part of Applied Energistics 2.
+ * Copyright (c) 2013 - 2014, AlgorithmX2, All rights reserved.
+ *
+ * Applied Energistics 2 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Applied Energistics 2 is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Applied Energistics 2.  If not, see <http://www.gnu.org/licenses/lgpl>.
+ */
+
+package appeng.me.helpers;
+
+
+import java.util.Optional;
+
+import net.minecraft.entity.player.EntityPlayer;
+
+import appeng.api.networking.security.IActionHost;
+import appeng.api.networking.security.IActionSource;
+
+
+public class MachineSource implements IActionSource
+{
+
+	private final IActionHost via;
+
+	public MachineSource( final IActionHost v )
+	{
+		this.via = v;
+	}
+
+	@Override
+	public Optional<EntityPlayer> player()
+	{
+		return Optional.empty();
+	}
+
+	@Override
+	public Optional<IActionHost> machine()
+	{
+		return Optional.of( this.via );
+	}
+
+	@Override
+	public <T> Optional<T> context( Class<T> key )
+	{
+		return Optional.empty();
+	}
+
+}