Added support for platforms to declare capabilities.

Platforms can declare certain capabilities and a suggested preference
for the platform for each capability. WorldEdit can then choose
the best platform for a given capability.

Examples of capabilities include providing configuration, registering
game hooks/events, performing changes to the world, or checking
permissions/authorization.

src/main/java/com/sk89q/worldedit/internal/ServerInterfaceAdapter.java

@@ -21,11 +21,17 @@ package com.sk89q.worldedit.internal;
 
 import com.sk89q.minecraft.util.commands.Command;
 import com.sk89q.minecraft.util.commands.CommandsManager;
-import com.sk89q.worldedit.*;
+import com.sk89q.worldedit.BiomeTypes;
+import com.sk89q.worldedit.LocalConfiguration;
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.ServerInterface;
+import com.sk89q.worldedit.extension.platform.Capability;
 import com.sk89q.worldedit.extension.platform.Platform;
+import com.sk89q.worldedit.extension.platform.Preference;
 import com.sk89q.worldedit.world.World;
 
 import java.util.List;
+import java.util.Map;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -87,6 +93,10 @@ public class ServerInterfaceAdapter extends ServerInterface {
         platform.onCommandRegistration(commands, manager);
     }
 
+    @Override
+    public void registerGameHooks() {
+    }
+
     @Override
     public LocalConfiguration getConfiguration() {
         return platform.getConfiguration();
@@ -107,6 +117,11 @@ public class ServerInterfaceAdapter extends ServerInterface {
         return platform.getPlatformVersion();
     }
 
+    @Override
+    public Map<Capability, Preference> getCapabilities() {
+        return platform.getCapabilities();
+    }
+
     /**
      * Adapt an {@link Platform} instance into a {@link ServerInterface}.
      *