Darktable 4.2.1

What's new in this version:

Changed:
- JPEG files are identified using magic bytes instead of file extension. This helps in cases where JPEG images end up in files with unexpected extensions.
- Allow shortcuts to be assigned to the "quick access" style and preset menus at the bottom of the darkroom view
- Add a collapsible section to the sigmoid module so that controls not used in standard processing scenarios are hidden by default
- Some minor modifications to image overlays in culling view to make them less intrusive

Fixed:
- Fix possible bad pinned memory transfer on OpenCL
- Fix bug in date/time sanitization function that caused image capture timestamps to be corrupted when they contained a time zone with a negative offset.
- Fix toast messages containing "%"
- Fix collections module using exclude rules when the first filter is empty
- Fix RGB curve histogram display when "compensate middle gray" is set
- Fix possible infinite loop when a module fails to load
- Properly honor "hide histogram" setting when restarting
- Fix darktable-chart crash
- Fix Y0 mask calculations in the demosaic module
- Avoid using fscanf() for loading configuration to avoid broken Windows implementation
- Add RYB vectorscope option to the darktable configuration file to ensure proper histogram view settings on startup
- Ensure that wide popups are properly shown on the same display as the associated widget
- Fix possible crash in camera tethering
- Make yes/no buttons in dialog boxes respond to standard shortcuts alt+y and alt+n
- Fix preferences sanitization, which was completely ineffective due to incorrect loading order
- Add a link to the sigmoid module's online documentation
- Fix tooltip on color calibration expander
- Fix incorrect reporting of HEIF image bit depth, which resulted in incorrect color profile selection for images without embedded color profile data
- Fix snapshot invalidation, which was too pessimistic and made switching snapshots slow
- Fix some messages in LUT module