Cleaned up nav_config Comments
Removed Leading Slash from PHP_DIR Constant Definition
Now Using Config Array to Construct Database

No longer used configured constants as Database configuration variables.

Now the config data is better encapsulated, and it is easier to created
multiple Database objects.
Updated Config for New Database Configuration

Accomodating changes in the way Database objects are instanciated.
Cleaned up Nav config too.
Changed the Initial Sequence when config is Loaded
Removed Unnecessary Nav Config Option

Default page was a option in the nav_config, but unneeded because of the
DEFAULT_PAGE constant.
Removed default_page Property from Nav.php