Adds an arrow in front of a expandable stream to expand and contract …

[abhaymaniyar]

…that stream.

Summary of changes When a user clicked on a stream in the stream pane, it narrows down the stream. Now if a user clicks on the stream it expands the stream and shows the topics that the stream contains. Screenshots or a brief video showing the change in action:

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[abhaymaniyar]

@Sam1301 Please review and help me to resolve merge conflicts.

[abhaymaniyar]

Thank you @saketkumar95 :). Can you please help me with the conflicts here?

[abhaymaniyar]

Thanks for reviewing @kunall17! Is there any variable in the code base which stores the number of topics in a stream?

[abhaymaniyar]

@kunall17 I am trying to implement what you said but there is a problem. I get the number of subjects in a stream only when I click on the stream. How can I get the number of subjects in a stream on launch of MainActivity?

[kunall17]

Yeah, true it only get's calculated when the expansion of the expandableListItem is done, so should we have arrow in all? Maybe show a message, no topics found?

[abhaymaniyar]

Great! I can do that.

[zulipbot]

@abhaymaniyar, your pull request has developed a merge conflict! Please review the most recent commit (f791888) for conflicting changes and resolve your pull request's merge conflicts.