Allow showing whole list of channels and not just by category

[je-vv]

Using 5.6 version on Arch, and one thing that really affects me is that I'm not able to see all channels for a particular m3u list. I need to select a category in order to see its channels, but that's often not what one wants since several channels offer a variety of programs, including sports, news, entertainment and yet films.

It'd be great that if no category is selected, then all channels are listed, and when selecting one category that list gets reduced of course according to the category. If that's too hard to achieve at once, perhaps offering an all category showing the whole list might be a way to offer the same, though it misses the effect of selecting/de-selecting a particular category.

If there's another way to achieve the same please let me know.

Thanks !

[DYefremov]

Sometimes this can actually be useful... Made a simple implementation.

Since the full lists can be quite large, I also added a small optimization for loading the channel list.

Best