Update MySql defaults

Author: mythz

src/ServiceStack.OrmLite.MySql/Converters/MySqlStringConverters.cs

@@ -5,7 +5,7 @@ namespace ServiceStack.OrmLite.MySql.Converters
 {
     public class MySqlStringConverter : StringConverter
     {
-        public MySqlStringConverter() : base(255) {}
+        public MySqlStringConverter() : base(8000) {}
 
         //https://stackoverflow.com/a/37721151/85785
         public override int MaxVarCharLength => UseUnicode ? 16383 : 21844;
@@ -15,7 +15,24 @@ public MySqlStringConverter() : base(255) {}
 
     public class MySqlCharArrayConverter : CharArrayConverter
     {
-        public MySqlCharArrayConverter() : base(255) { }
+        public MySqlCharArrayConverter() : base(8000) { }
+
+        public override string MaxColumnDefinition => "LONGTEXT";
+    }
+    
+    public class MySql55StringConverter : StringConverter
+    {
+        public MySql55StringConverter() : base(255) {}
+        
+        //https://stackoverflow.com/a/37721151/85785
+        public override int MaxVarCharLength => UseUnicode ? 16383 : 21844;
+
+        public override string MaxColumnDefinition => "LONGTEXT";
+    }
+
+    public class MySql55CharArrayConverter : CharArrayConverter
+    {
+        public MySql55CharArrayConverter() : base(255) { }
 
         public override string MaxColumnDefinition => "LONGTEXT";
     }

src/ServiceStack.OrmLite.MySql/MySqlDialectProvider.cs

@@ -42,6 +42,8 @@ public override IDbConnection CreateConnection(string connectionString, Dictiona
         public MySql55DialectProvider()
         {
             RegisterConverter<DateTime>(new MySql55DateTimeConverter());
+            RegisterConverter<string>(new MySql55StringConverter());
+            RegisterConverter<char[]>(new MySql55CharArrayConverter());
         }
 
         public override IDbDataParameter CreateParam()