Declare window controller as a window delegate.

The browser window has its delegate set to its controller in their XIB
file. This fix makes the connection officially work, although no
delegate overrides are currently written.
Improve notifications during resource loading.

Add an error attribute to notifications sent from browser window
controllers when a resource load fails.
Implement the Get-URL Apple event.

Add a method to the application delegate to handle the Apple event for
incoming URL-access requests. Register said method for that event type.
Off-load the handling to a new NSOperation subclass.

Register the application as handling a common URL scheme, for testing
purposes.
Use (optional) search string when opening files.

Add support for extracting the search string from an open-document
Apple event. Change the file-open NSOperation subclass to initiate a
search, for the extracted string, in each successfully opened
(non-printing) file.
Redo file opening/printing.

Replace the NSOperation subclass handling opening & printing with a
regular class that uses only notifications and delayed sends to run the
state machine.

Add a missing method declaration.
Redo Get-URL implementation.

Replace the NSOperation subclass handling opening URLs with a regular
class that uses only notifications and delayed sends to run the state
machine.
Renamed file-opening/printing class.
Add open-then-print menu command.

Add alternate menu command for Print that brings up an Open panel then,
if not cancelled, opens the selected files in new browser windows and
then, if not cancelled from the Print panels brought out next, prints
from those windows. Serve as a way to test the Print-Document Apple
event with minimal fuss.