Add support for extended BlockStates.

Extended BlockStates include extra properties about a given location such
as if a podzul dirt block is covered by snow or a fence is connected to
other fences.

There are currently 2 ways to retrieve an extended BlockState :

1. From a BlockSnapshot by calling getExtendedState.
2. From a BlockState by calling withExtendedProperties. This method should
only be called on live BlockStates and may not work correctly if used
with a BlockSnapshot such as during a ChangeBlockEvent.

src/main/java/org/spongepowered/api/block/BlockSnapshot.java

@@ -43,6 +43,15 @@ public interface BlockSnapshot extends LocateableSnapshot<BlockSnapshot> {
      */
     BlockState getState();
 
+    /**
+     * Gets the extended {@link BlockState}. This applies extended properties
+     * that are usually located around the associated {@link BlockType}. Check
+     * {@link BlockState#withExtendedProperties(Location)} for more info.
+     *
+     * @return The extended BlockState
+     */
+    BlockState getExtendedState();
+
     /**
      * Creates a copy of the {@link BlockSnapshot} with the provided 
      * {@link BlockState}. Any additional data associated with a

src/main/java/org/spongepowered/api/block/BlockState.java

@@ -59,6 +59,29 @@ public interface BlockState extends ImmutableDataHolder<BlockState>, DirectionRe
      */
     BlockType getType();
 
+    /**
+     * Applies extended properties for the current @{link BlockType} if any to 
+     * the current {@link BlockState}. This usually is gathered from surrounding
+     * {@link BlockState}'s.
+     * 
+     * <p>Note: This should only be called for live {@link BlockState}'s at
+     * a specific {@link Location} for accurate results.</p>
+     * 
+     * <p>
+     * Examples of some extended properties are:
+     * </p>
+     *
+     * <ul>
+     *     <li>snow on podzul dirt block</li>
+     *     <li>occupied status for beds</li>
+     *     <li>fence connections</li>
+     * </ul>
+     * 
+     * @param location The location used to search for extended properties
+     * @return The blockstate with extended properties included if any
+     */
+    BlockState withExtendedProperties(Location<World> location);
+
     /**
      * Gets the associated {@link BlockState} with the cycled
      * {@link BaseValue}. Note that only {@link Cycleable} values can be