Release v.2.3.0

• Support for WITH statements and Common Table Expressions(CTE). Sample usage.
• [postgres] Support for ON CONFLICT clause (sample)
• [mysql] Support for ON DUPLICATE KEY UDPATE clause (sample)
• New type-safe SET clause for UPDATE statement (sample)
• Generated files idempotency (timestamp removed from generated files) (issue)
• Automatic query logging (sample)