Update dbinterface class to use PDO and fix some broken SQL.

[steve-lad]

Update to PDO model. Improves clarity and eliminates need for unnecessary quoting.

Restructure to improve readability

Modify calls to dbinterface class to reduce post processing

Use PDO bindParam to speed execution and ensure data integrity

Save sccpsettings to DB after initial constructor call in Sccp_manager class

Fix some broken SQL statements.

Add some annotations to help in future

Atom whitespace removal

[steve-lad]

Merged into PR108