Support utf8mb4 if the database does. Fixes #535

What MySQL calls "UTF8" is actually a subset of the full unicode specification.
It doesn't accept 4-byte UTF-8 characters.  Proper support is called "utf8mb4"
and is, these days, fairly common (Ubuntu 10.04LTS's bundled MySQL does not
support it, but later ones do)

Detection of utf8mb4: "SHOW CHARACTER SET WHERE charset='utf8mb4';" returns at
least one row

Conversion of pre-existing DBs: this was easy, we already had code in the
updater for this for when we started enforcing utf8. It was version-bumped and
set to update to either utf8mb4 or utf8, depending

Making it use utf8mb4 in the database connection: Actually hard.  Connector/J
5.1.13 or newer should autodetect this, but in my testing it didn't
(http://dev.mysql.com/doc/relnotes/connector-j/en/news-5-1-13.html)

As such, if utf8mb4 has been detected, I've added code that should manually
execute "SET NAMES utf8mb4;" on all new connections.

If a database does not support utf8mb4 (rare these days) I've added code to
strip these characters before DB insertion; they won't be recorded correctly,
but it'll avoid the exception from issue #535

src/main/java/de/diddiz/util/LoggingUtil.java

@@ -4,6 +4,7 @@ import de.diddiz.LogBlock.Actor;
 import de.diddiz.LogBlock.Consumer;
 import de.diddiz.LogBlock.Logging;
 import static de.diddiz.LogBlock.config.Config.getWorldConfig;
+import static de.diddiz.LogBlock.config.Config.mb4;
 import de.diddiz.LogBlock.config.WorldConfig;
 import java.util.List;
 import org.bukkit.Location;
@@ -200,4 +201,10 @@ public class LoggingUtil {
 		// Do this down here so that the block is added after blocks sitting on it
 		consumer.queueBlockBreak(actor, origin.getState());
 	}
+	
+	public static String checkText(String text) {
+		if (text==null) return text;
+		if (mb4) return text;
+		return text.replaceAll("[^\\u0000-\\uFFFF]", "?");
+	}
 }