Added priority getter to NamedBlock interface.

src/main/java/li/cil/oc/api/driver/NamedBlock.java

@@ -21,4 +21,20 @@ public interface NamedBlock {
      * @return the preferred name.
      */
     String preferredName();
+
+    /**
+     * This is used to determine which name to use in case multiple
+     * environments with this interface are merged.
+     * <p/>
+     * If multiple named environments are merged the one with the
+     * <em>highest</em> priority is selected. Negative values are
+     * allowed. The recommended default value is therefore zero.
+     * <p/>
+     * If multiple environments with the same priority exist, the
+     * result is unspecified. It will usually result in the environment
+     * of the driver that was registered first.
+     *
+     * @return the priority with which to use this name.
+     */
+    int priority();
 }

src/main/scala/li/cil/oc/server/driver/CompoundBlockDriver.scala

@@ -30,9 +30,10 @@ class CompoundBlockDriver(val blocks: driver.Block*) extends driver.Block {
   }
 
   private def tryGetName(world: World, x: Int, y: Int, z: Int, environments: Seq[ManagedEnvironment]): String = {
-    for (environment <- environments) environment match {
-      case named: NamedBlock => return named.preferredName
-      case _ =>
+    environments.collect {
+      case named: NamedBlock => named
+    }.sortBy(_.priority).headOption match {
+      case Some(named) => return named.preferredName
     }
     try world.getTileEntity(x, y, z) match {
       case inventory: IInventory if !Strings.isNullOrEmpty(inventory.getInventoryName) => return inventory.getInventoryName.stripPrefix("container.")