PSPreferencesController.[hm]: Added support for registering hot keys;
not the most elegant thing in the world, but much better than it was
in the prototype. Triggered by +readPreferences.
NJRHotKeyField.[hm]: Replaced model components (wow, was that ever
dumb) by NJRHotKey reference, eliminating cumbersome archiving model.
Added accessors for hot key.
NJRHotKeyManager.[hm]: Ported Quentin Carnicelli's HotKeyCenter code
to use NJRHotKey, cleaned up, and removed reverse-engineered pre-10.2
support.
NJRHotKey.[hm]: New. Provides Cocoa-centric storage for
three-component hot keys, mapping from Cocoa to Carbon modifiers.
PSApplication.m: Reorganized. Added invocation of
+[PSPreferencesController readPreferences].
Fixes bug 29.
