[dvbviewer] Update to 1.10.28

[manuelm]

Changes:

• added recording reader: Allows playback of ongoing recordings. There are still some minor quirks. e.g. In case we reach the end during playback/seek we'll sleep until the next refresh. This should happen once but sometimes this happens twice.
• added support for putting outline before plot
• removed custom notification if backend is unavailable
• fixed a bug where a new timer has been removed and re-added again shortly after it has been added the first time
• more code re-factorization