Refactor Stream's activateNext function

[MeoMix]

This function is pretty integral to Streamus' functionality and it needs a lot of love.

First off, it's huge. Break it apart into smaller functions.

Additionally, I need to be able to 'getNext' without actually activating next. This is made more difficult because of stuff like 'shuffle' and 'radio mode'. You can't call 'getNext' with shuffling enabled and have it return a different result each time. It needs to return the same result each time. So, a lot of work needs to go into pre-determining the order of (at least) the next few items.

Once this is done, also add functionality to chromeIconManager so that it can show what song will be played next. This is really useful information throughout the entire app.