WYSIWIG for Videos: Import Videos with Excel Timeline

see https://confluence.translate5.net/display/MI/WYSIWYG+for+videos
see https://confluence.translate5.net/display/MI/Concept+for+Locaria%3A+WYSIWYG+for+images+and+videos

PHP Extension for FFMPEG:

https://github.com/PHP-FFMpeg/PHP-FFMpeg

Additional Infos:

• Video-Import only, when the visual plugin is active
•  Until a conversion is implemented the only supported format is "mp4"
• Details: see Concept "1) Import Basis": https://confluence.translate5.net/display/MI/WYSIWYG+for+videos 
• When Visual not active or Segments/Timecodes invalid or Video-Spec does not match: Reject Import

Branch is: TRANSLATE-2666-2671-visual-image-video