Automatically handle Unicode servers; stub out login handling
There's a lot going on in this change:
* Fixed a bug where charset was always set to none
* Added protocol on PLSOverseer so that something can properly handle login errors
* PLSAppDelegate implements stubs for the PLSOverseer protocol
* PLSOverseers automatically configure themselves for Unicode servers now
* Ripped out handleCommonErrors: because it turns out I want to handle the
same error in multiple ways.
Next step is to properly handle 'p4 login' and request a password.