Expose MySqlDbType

[bgrainger]

The integer values of MySqlDbType are exposed by Connector/NET in GetSchemaTable (#307) and GetSchema (#361). MySqlParameter also has a MySqlDbType property.

Clients may be relying on the presence of this type in the public API and on its exact values.

[Thorium]

Would it be enough to rename MySql.Data.Serialization.ColumnType to MySql.Data.MySqlClient.MySqlDbType and modify the visiblity from internal to public with Visual Studio rename tool?

Or do the internal types have to match the MySql.Data types:

	public enum MySqlDbType
	{
		Decimal,
		Byte,
		Int16,
		Int24 = 9,
		Int32 = 3,
		Int64 = 8,
		Float = 4,
		Double,
		Timestamp = 7,
		Date = 10,
		Time,
		DateTime,
		[Obsolete("The Datetime enum value is obsolete.  Please use DateTime.")]
		Datetime = 12,
		Year,
		Newdate,
		VarString,
		Bit,
		JSON = 245,
		NewDecimal,
		Enum,
		Set,
		TinyBlob,
		MediumBlob,
		LongBlob,
		Blob,
		VarChar,
		String,
		Geometry,
		UByte = 501,
		UInt16,
		UInt24 = 509,
		UInt32 = 503,
		UInt64 = 508,
		Binary = 600,
		VarBinary,
		TinyText = 749,
		MediumText,
		LongText,
		Text,
		Guid = 800
	}

[bgrainger]

ColumnType (an enum expressing values used in the MySQL protocol) should be kept separate from MySqlDbType (a separate enum used in the public API, that must maintain compatibility with Connector/NET).

A lot of the values will probably overlap (because MySql.Data may conflate the two enums).

[Thorium]

Yes I noticed MySqlDbType is missing column types like int and char. They are valid types however, that's why they need to be in GetSchema()

[bgrainger]

Implemented in 0.29.0.