Make database extension code object oriented
As DBI_Extensions are not classes we can mock them for tests.
Convert database interface to a class
Fix tests by using mock objects of DatabaseInterface
Merge branch 'master' into OOP_DBI
Few renamings that got missed
Set MaxNavigationItems value irrespective of it being set earlier
Missing renamings
Merge pull request #1 from lem9/OOP_DBI

Missing renamings
Some more missing renamings
isSuperuser() is also a part of DatabaseInterface class
Make related functions and integral part of DatabaseInterface class
These constants are better as a part of DatabaseInterface class
Fix indentation
Separate DatabaseInterface class and creation of an instance of it
Merge branch 'master' into OOP_DBI

Conflicts:
	libraries/database_interface.lib.php
Couple of renamings that got missed
Merge pull request #401 from madhuracj/OOP_DBI

OOPing the database interface