Separately set which channels should be autojoined at startup

[zarino]

Right now, channels listed in the settings.json are all joined at startup.

For channels I don't regularly access, I prefer having them listed in the sidebar but not joined automatically.

It's most future-proof to change the channels property of the settings file, from a list of strings (channel names) to a list of objects, which contains the channel's settings, like:

{
  "servers": [
    {
      "name": "Freenode",
      "url": "irc.freenode.net",
      …
      "channels": [ 
        {
          name: "#bots", 
          autoJoin: false
        },
        {
          name: "#poplus",
          autoJoin: true
        }
      ]
    },
  "keywords": [ "tannoy" ]
}