Fixed Schema manager accepts length for blob/text column types

[Xon]

Affected version

2.0.4

If a length is set, getColumnDefinitionSql will attempt to include a length argument for blob (TINYBLOB/MEDIUMBLOB/LONGBLOB/BLOB) and text (TINYTEXT/MEDIUMTEXT/LONGTEXT/TEXT) column types. Which is invalid, and give a fairly non-obvious MySQL error message