In general it's almost copy/paste of MySqlBatchRunner class.
Slight modifications:
- changed queries to postgresql syntax
  UPDATE <what to update>
  SET <expression>
  FROM ( <generated select query> )
- slighly modified regular expression with self updates.
  ColumAlias is optional group now. Alias is not generated every time.
- When in TransactionScope it means we have open transaction, really, it is.
  Postgre treats such transaction as distributed, that's why opening new transaction fails.

- Previously we detected outside transactions using System.Transaction, but recently
  we overcame the issue using specific configuration of the PgSql devart provider.
  It's redundant code now and should be removed to make everything consistent
  with the rest of the code.

- Table and column names that are not lowercase are caused the error. So it's necessary
  to put them in quotes.
  More info here
  http://www.postgresql.org/docs/current/interactive/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS