- Patch #443422 by yched, bjaspan | chx, merlinofchaos, Scott Reynolds, plach,...

- Patch #443422 by yched, bjaspan | chx, merlinofchaos, Scott Reynolds, plach, profix898, mattyoung: added support for pluggable 'per field' storage engine. Comes with documentation and tests.

The Field Attach API uses the Field Storage API to perform all "database access". Each Field Storage API hook function defines a primitive database operation such as read, write, or delete. The default field storage module, field_sql_storage.module, uses the local SQL database to implement these operations, but alternative field storage backends can choose to represent the data in SQL differently or use a completely different storage mechanism such as a cloud-based database.