User Guide - DB Driver Reference

First stab at DB driver reference. Methods are listed in order encountered in the source file.
Parameter or return types in DB_driver updated as needed, and reflected here.
TOC entry added to bottom of database index page.
Signed-off-by:James L Parry <jim_parry@bcit.ca>
Fix Issue #3417
Remove trailing newline
Merge pull request #3418 from warpcode/develop

Fixes #3417
Fix #3419
Merge pull request #3416 from jim-parry/userguide/db_driver_reference

User Guide - DB Driver Reference
Fixed typo
Merge pull request #3420 from albertleao/patch-1

Fixed typo
Extend fix for #3419
Add support for configuring socket pipe connections in 'mysqli'

Supersedes PR #3415