So we had a couple copies of a Platform enum, so now there's a public
one in the common module. It wasn't possible to specify what platform
the GameData is, so now it's part of initialization. While I'm at it,
remove the stupid reload_repositories() requirement and make that a
private part of the API.
* Move PlatformId to common module.
* Platform id is no longer hardcoded to win32.
* Parse apply options correctly.
* Parse target info better, use more native structures.
* All errors are now handled properly, and propagated up.
* Added a new Region enum.
* Added todo!() to all unhandled patching branches.
* Paths are now built using PathBuf instead of format!().
* process_patch function is no longer accessible, now you have to use
the function found in GameData and BootData.
