Stitch segment that is not a break

[birme]

Add the option to stitch a segment that is not a break. It should be handled the same way as a break in terms of the stitching but no Ad avail makers should be inserted in this case.

It should also be possible to combine an array of segments with array of breaks. Suggested example payload:

{
  "uri": "https://maitv-vod.lab.eyevinn.technology/VINN.mp4/master.m3u8",
  "segments": [
    { "pos": 0, "duration": 5000, "url": "https://maitv-vod.lab.eyevinn.technology/preroll/test-5s.mp4/master.m3u8" }
  ],
  "breaks": [
    { "pos": 5000, "duration": 15000, "url": "https://maitv-vod.lab.eyevinn.technology/ads/apotea-15s.mp4/master.m3u8" }
  ]
}

This feature is needed to resolve the request in EyevinnOSC/community#30