SIL.Windows.Forms.Archiving 16.1.0

• .NETFramework 4.6.2

  • Markdig.Signed (>= 0.37.0)
  • SIL.Archiving (>= 16.1.0)
  • SIL.Core (>= 16.1.0)
  • SIL.Core.Desktop (>= 16.1.0)
  • SIL.Windows.Forms (>= 16.1.0)
  • SIL.WritingSystems (>= 16.1.0)
  • System.IO.Compression (>= 4.3.0)
  • System.IO.Compression.ZipFile (>= 4.3.0)

• .NETFramework 4.8

  • Markdig.Signed (>= 0.37.0)
  • SIL.Archiving (>= 16.1.0)
  • SIL.Core (>= 16.1.0)
  • SIL.Core.Desktop (>= 16.1.0)
  • SIL.Windows.Forms (>= 16.1.0)
  • SIL.WritingSystems (>= 16.1.0)
  • System.IO.Compression (>= 4.3.0)
  • System.IO.Compression.ZipFile (>= 4.3.0)

Changes since version 16.0.0

Added:
- [SIL.Windows.Forms] Added PortableClipboard.CanGetImage()
- [ClipboardTestApp] Restored this test program and added tests for PortableClipboard.CanGetImage() and GetImageFromClipboard()
- [SIL.Windows.Forms] Added SILAboutBox.Navigating and SILAboutBox.Navigated events to allow callers to customize how HTML links in the embedded browser are handled.
- [SIL.Windows.Forms] Added SILAboutBox.AllowExternalLinksToOpenInsideAboutBox property to control whether a `<base target="_blank" rel="noopener noreferrer">` line is automatically added to the HTML (if missing) to ensure links open in the system browser rather than within the About dialog box.
- [SIL.Core] Added static HtmlUtils class with methods for handling HTML to be displayed in browser controls (e.g., `SILAboutBox`), including support for fixing missing target attributes on links and copying simple asset files when creating a temp HTML file to display.

Fixed:
- [SIL.Windows.Forms] In `CustomDropDown.OnOpening`, fixed check that triggers timer to stop.
- [SIL.Windows.Forms] Fixed HtmlBrowserHandled.OnNewWindow to open external URLs (`target="_blank"`) in the system’s default browser instead of Internet Explorer. This improves behavior in SILAboutBox and other components that use the embedded browser.

Changed:
- [SIL.WritingSystems] Updated embedded langtags.json
- [SIL.WritingSystems] Updated embedded ianaSubtagRegistry.txt
- [SIL.Windows.Forms] Improved SILAboutBox to help prevent navigation issues when the supplied HTML contains links but lacks both a `<base target="_blank">` element and explicit `target="_blank"` attributes on the links. If the Navigating event is not handled, such links would otherwise open within the About box itself, often resulting in unexpected behavior. A sensible fallback is now applied automatically to the HTML, and in debug mode, a developer warning is shown.
- [SIL.Windows.Forms] Documented previously undocumented feature: SILAboutBox constructor can accept either a filename or a file URI.

See full changelog at https://github.com/sillsdev/libpalaso/blob/master/CHANGELOG.md