Initial implementation of a simple dvr

[fmatt]

Initial implementation of a simple dvr. Tasks:

• [x] capture direct usb stream without interfering with live stream
• [x] mux stream into one single file per received stream and save to Pictures/Digiview
• [ ] storage limit check
• [x] pick up left over stream dumps and mux them
• [ ] show indicator during muxing latest recording
• [ ] ability to disable automatic recording
• [x] show recording indicator
• [ ] override oldest recording after configurable number of videos