Nightly build from 2026-02-16-03-36-46

Add language selector to video track options in GUI

The lang parameter was already supported in the meta file for all track
types, but the GUI only exposed a language combo box for audio/subtitle
tracks. This adds a matching selector to the video tab so users can set
or edit the language of video tracks as well.

Release 2.7.1

tsMuxeR 2.7.1

• Fixed file dialogs not appearing on macOS.
• Fixed browse button for output folder passing wrong parameter to file dialog
• MacOS now a Universal binary!
• Linux release includes GUI.
• Dropped Windows XP support.