WinGui: Switching the preset format over to JSON and adding a container object for the presets which should make the archiving of presets when the app is unable to load them a bit more reliable. The app will try and bring forward the settings it can, but will not migrate ones it can't. 

Backup your presets before updating to this build incase something goes wrong!

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6599 b64f7644-9d1e-0410-96f1-a4d463321fa5