make source devices dynamic, fixes bug #1

[Tsjippy]

make source devices dynamic, fixes bug #1

[dnpwwo]

@Tsjippy ,

Dynamic source is a really interesting idea, I like the fact that it customises Domoticz to what the user uses. From reading the code I assume that switching Apps from Domoticz will work as before?

A couple of things:

1. Rather than commenting out the log line in the UpdateDevice could you make it a Domoticz.Debug() call instead? Sometimes it is useful to know if Domoticz is asked to update in my experience.
2. Could you increment the plugin version number and update the readme
3. I don't think using _plugin.appOptions in syncDevices is the way to go. I have 2 chromecasts and 2 google home minis and the source list for each of them could be different depending who in my family uses them. If the plugin Source is going dynamic then the new 'App' should be added to the Device's own 'LevelNames' and other device options should be preserved