To facilitate local hacking, RT needs a mechanism to allow site administrators
to easily add HTML templates for the web ui and to replace sections
of code in RT's core modules _without_ having to modify those modules

We'll use several methods to achieve this goal.

	Webui
		HTML::Mason allows users to create multiple
component hierarchies.  RT should ship with a local component root
defined and available. This root should be configured as the "primary"
component root.


	Core modules

	This gets a bit trickier. we want to allow people to trivially
subclass core modules and to use those subclasses throughout the code.

The way we're going to handle this is by setting up a number of subroutines
in config.pm that look something like this:

sub NewTicketObj {
	eval "require $TicketClass";
	my $object = new $TicketClass;
	return ($object);
}

# This variable is used for ref type checking
$TicketClass = "RT::Ticket";

we could use an eval around the require and thus completely avoid specifying
the object in two places. which feels like a win. but i'm worried about perf.