Add extended support for me.topArtists & me.topTracks endpoints

[r-bbn]

Hello ! I am currently using this really useful lib in a flutter project around the spotify API, thanks ! However, features are really limited when we want to retrieve users' top items because we could not use specific values for the parameters stated here (limit, offset & time_range) : https://developer.spotify.com/documentation/web-api/reference/#/operations/get-users-top-artists-and-tracks

Hence, I did simple modifications to the functions me.topArtists() and me.topTracks() so that I could use them in my project :)

Here is the detail of my modifications :

• Add support to use specific values for the parameters ""limit", "offset", & "time_range"
• Add comments to explain the use of the functions with a reference to the Spotify Web API endpoint documentation (Get User's Top Items)
• Modify the call of the me.topTracks()endpoint in the deprecated function users.topTracks()

[hayribakici]

@rinukkusu This PR can be closed now, no?

[rinukkusu]

@hayribakici Yes, right! @r-bbn @Quatton We took your ideas, refined them and the improvements have been merged with PR #157 to move things forward. Thank you for your contributions!

[Quatton]

Thank you!