Misc fixes.

Closes a few old youtrack issues which I don't remember because I had
like 30 tabs open, and a few other issues which I found while testing
some of those.

worldedit-core/src/main/java/com/sk89q/worldedit/function/GroundFunction.java

@@ -85,9 +85,9 @@ public class GroundFunction implements LayerFunction {
         if (depth == 0) {
             if (function.apply(position)) {
                 affected++;
+                return true;
             }
         }
-
         return false;
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/internal/command/exception/WorldEditExceptionConverter.java

@@ -61,7 +61,7 @@ public class WorldEditExceptionConverter extends ExceptionConverterHelper {
     }
 
     private CommandException newCommandException(String message, Throwable cause) {
-        return new CommandException(TextComponent.of(message), cause, ImmutableList.of());
+        return new CommandException(TextComponent.of(String.valueOf(message)), cause, ImmutableList.of());
     }
 
     @ExceptionMatch

worldedit-core/src/main/java/com/sk89q/worldedit/session/SessionManager.java

@@ -261,6 +261,7 @@ public class SessionManager {
      */
     public synchronized void unload() {
         clear();
+        timer.cancel();
     }
 
     /**

worldedit-core/src/main/java/com/sk89q/worldedit/util/formatting/component/SchematicPaginationBox.java

@@ -46,7 +46,7 @@ public class SchematicPaginationBox extends PaginationBox {
 
     @Override
     public Component getComponent(int number) {
-        checkArgument(number < files.length - 1 && number >= 0);
+        checkArgument(number < files.length && number >= 0);
         File file = files[number];
         Multimap<String, ClipboardFormat> exts = ClipboardFormats.getFileExtensionMap();
         String format = exts.get(Files.getFileExtension(file.getName()))