Improve upperCaseFirst stability.

src/com/massivecraft/mcore/util/Txt.java

@@ -209,6 +209,8 @@ public class Txt
 	
 	public static String upperCaseFirst(String string)
 	{
+		if (string == null) return null;
+		if (string.length() == 0) return string;
 		return string.substring(0, 1).toUpperCase()+string.substring(1);
 	}