Remove double spaces from shaders' names in settings.
Use consistent settings names.
Rename "SnapShot" to "Snapshot".
Change old strings to MPC-HC.
Change "Gabest" to "MPC-HC".
Installer: change more strings and remove the old keys when uninstalling.
CMPlayerCApp: Migrate settings from old to the new registry location.

Only when we're creating the MPC-HC key for the first time.
Installer: minor refactoring
CMPlayerCApp: Don't delete the old key, depend on the existence of the ExePath value instead of the key and migrate the settings to the new format.