Add a minimal fix for numeric types

Author: fredericDelaporte

src/NHibernate/Type/ByteType.cs

@@ -54,7 +54,7 @@ public override string Name
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToByte(value).ToString();
 		}
 
 		// 6.0 TODO: rename "xml" parameter as "value": it is not a xml string. The fact it generally comes from a xml

src/NHibernate/Type/DecimalType.cs

@@ -66,7 +66,7 @@ public override object FromStringValue(string xml)
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToDecimal(value).ToString();
 		}
 
 		// 6.0 TODO: rename "xml" parameter as "value": it is not a xml string. The fact it generally comes from a xml

src/NHibernate/Type/DoubleType.cs

@@ -66,7 +66,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToDouble(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/Int16Type.cs

@@ -114,7 +114,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToInt16(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/Int32Type.cs

@@ -114,7 +114,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToInt32(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/Int64Type.cs

@@ -114,7 +114,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToInt64(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/SByteType.cs

@@ -116,7 +116,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToSByte(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/SingleType.cs

@@ -91,7 +91,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToSingle(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/UInt16Type.cs

@@ -114,7 +114,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToUInt16(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/UInt32Type.cs

@@ -114,7 +114,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToUInt32(value).ToString();
 		}
 	}
 }

src/NHibernate/Type/UInt64Type.cs

@@ -113,7 +113,7 @@ public override object DefaultValue
 
 		public override string ObjectToSQLString(object value, Dialect.Dialect dialect)
 		{
-			return value.ToString();
+			return Convert.ToUInt64(value).ToString();
 		}
 	}
 }