Add support for chromecast

[fivestones]

Before posting

Please follow the steps below and check the boxes with [x] once you did the step.

[x ] I checked the issue tracker for similar issues
[x ] I checked the changelog if the issue is already resolved
[x ] I tried the latest Clementine build from here

System information

Please provide information about your system and the version of Clementine used.

Operating System: OSX
Clementine version: 1.3.1

Expected behaviour / actual behaviour

GIVEN Clementine player is running WHEN music is playing THEN I expect to see a cast icon show up in greyed out form if no chromecast is found AND THEN I expect to see a cast icon in a color other than grey if one or more chromecast devices is found

GIVEN Clementine player is running with at least one chromecast found WHEN I click on the enabled cast icon THEN I expect to pick from a list of device to cast to

GIVEN User clicks on an activated chromecast icon WHEN I the device to cast to THEN audio streams to the chosen chromecast device AND THEN I expect to see an identifier of song title and clementine on the Screen for video enabled cast devices AND THEN I expect the screen to have some sort of screensaver (milkdrop?!) for video enabled cast devices.

Note: I posted the exact text of an issue from 2016 posted by dkiser, since it is the exact issue I am facing. That issue was closed because there was no API for chromecast at that time, and so this was not feasible. Now this is feasible, as demonstrated by this exact feature in VLC and other apps. For example code of how to go about doing it, see Mkchromecast (https://github.com/muammar/mkchromecast.git)

[fivestones]

It's been over a year. Any chance of progress on this?

[majjhima]

I just found VLC can send music to a chromecast device which is great, but I much prefer the Clementine player and would also love to see chromecast support added.

[Fooughhy]

Is this worked on at all?