Harmonize coding style and whitespace
Reorganized Dialog.mm

Mainly ensure that the class implementations follows their interface declarations.
Remove commented out code
Remove workaround for signatureWithObjCTypes:

This method was made available in 10.5 along with documentation.
NSReleasePool → @autoreleasepool
Update to ARC
Use Foundation (Core) data types
Use Objective-C literals
Remove mention of Carbon
Use new APIs for reading/writing plists

The previous APIs were deprecated because they do not follow proper Cocoa memory management rules.