AllEpisodes Page updates

[thigg]

For this PR I'm especially happy to get your reviews.

• centralized the model of the allepisodes page to Main.qml, so its loaded only once at startup
• during startup the PodcastsPage is showing a loading indicator therefore
• setting the query results in an update of the model, this is done anyway at every call
• renamed couple methods to be more expressive (maybe should rename setQueryFilterEx as well...)
• writing the last selected filter to the config, thus its persisted across starts and pageloads

I'm going to finish here for now until the other PRs are merged. When this is all done and settled I will open new PRs with the other missing stuff I did. Future work should also include unifying the both pages for showing the episodes. Maybe this can be done via an extended filter mechanism. (Showing the episodes of an podcast is the same as filtering for the podcast)

This isn't based on the most up-to-date master, as I cant deploy it in my emulator.

[thigg]

At least most of the things are interdependent, or at least belongs to the same feature. (loading indicator is needed because the load time is now a longer)

If you see things that you would like in a separate PR, I can try.

[thigg]

bump, any new comments?

[thigg]

Hey, can we get this done soon? I closed the comment in the review, to make clearer that, from my side, this is complete, as I dont know a better solution to the discussed part.

[thigg]

@Keeper-of-the-Keys @sfbg anyone? I'd like at least a comment that this repo is still alive and maintained, because otherwise I would waste my time here.

[Keeper-of-the-Keys]

@thigg I seem to have merged too early - the connections don't work with the passed id the way you implemented it, trying to see how to fix.

[Keeper-of-the-Keys]

Several things:

1. the id can't be passed the way that it is as far as I can tell
2. somehow util.js is not defined in the allpodcastsepisodes scenario, even if I add two different connection objects ReferenceError: Util is not defined

For now I'm reverting this merge, we're clearly not ready for 2 models to co-exist (I'm also not sure how much benefit it provides when you can at most display one at a time to have 2 co-existing models eating up memory on an OS with an overactive OOM-killer).