PPageMisc: Display a message in case no customized keys are present.
PPageMisc: Change filename for export keys.
MPC: Delete settings export registry file in case of failure.
MPC: Export settings now takes a path instead of displaying a save dialog.
DSUtil: ExportRegistryKey now sets GetLastError().
use the type specifier instead of a cast for float
build.bat: reindent
cosmetics: use the xml end tag where possible
update Inno Setup Turkish translation
Add the ability to choose the scale factor for the auto-fit zoom.

The factor is relative to the screen size.
Prevent black lines from appearing on the sides of the video when resizing.

This happened mostly when resizing manually or when using auto-fit zoom.

Fixes #2423.
FFAudioDecoder: Register a lock manager for thread-safety of avcodec functions.