implemented NSDocument class methods +readableTypes, +writableTypes, + isNativeType: in -[NSDocument setFileName:] do not call -[NSURL fileURLWithPath:] if the path parameter is nil
implemented NSDocument class methods +readableTypes, +writableTypes, + isNativeType:
in -[NSDocument setFileName:] do not call -[NSURL fileURLWithPath:] if the path parameter is nil

git-svn-id: 728ffa388f20071a20a4b19b45cfa0b6da7e7a99@438 43251c19-cd1f-0410-9ec0-95c558c233a8

wenq1/cocotron,farcaller/cocotron