ChannelSwitch should start a new txtreceiver on selected channel if a tuner is available

[vdr-projects]

ChannelSwitch should start a new txtreceiver on selected channel if a tuner is available

[pbiering]

work already started in a private branch (not public so far because not ready for alpha testing)...

Test cases:

1. start TT -> switch to non-live channel
   stop live receiver
   case:
   - no free tuner available -> stay in "cached" mode
   - free tuner available -> start receiver -> change to "tuned" mode

2. while in "tuned" mode -> something else requests tuner with higher priority (e.g. a started recording) -> stop receiver -> switch back to "cached" mode, stay there even a tuner get free'ed later

[pbiering]

Sneak preview of alpha version: https://github.com/pbiering/vdr-plugin-osdteletext/tree/2.1.0-second-tuner

Test case 1 is working

[pbiering]

Test case 2 is not a case at all because VDR occupies even the live tuner for recording and triggers a live channel switch similar to keystroke on remote, which is also selecting new live channel teletext.

alpha version turned now into beta, please test