fuel/core — pull request #800 by antitoxic (2012-01-29 18:11:36+00:00)
Title: Feature: Nested db transactions

Allowing the multiple `\DB::start_transaction()` usage, so that saving of objects can be delegated to autonomous methods.

#### Reference:
- http://blog.ekini.net/2010/03/05/zend-framework-how-to-use-nested-transactions-with-zend_db-and-mysql/
- http://framework.zend.com/wiki/display/ZFPROP/Nested+Transaction+Support+for+Zend_Db_Adapter_Abstract+-+Bryce+Lohr