Introduce collaborative playlist support

Thanks to @samuelrey for this PR :)

Introduces a new method for creating a collaborative playlist.

v1.2.0

Support for GetShow and GetShowEpisodes introduced, many thanks to @davidiola

v1.1.2: Fix spelling of a JSON key (#155)

The JSON key for the item object in the CurrentlyPlaying struct is now in lowercase. See https://developer.spotify.com/documentation/web-api/reference/#endpoint-get-the-users-currently-playing-track

V1.1.1: Fixes

This release contains no breaking changes!

Changes

Change the page implementation to use a pointer receiver for panic safety

Previously, a value receiver was used which allowed developers to pass a value into the NextPage and PreviousPage methods. This would result in a panic due to the underlying implementation relying on reflection. This now is impossible, and code that could cause a panic will now no longer compile.

Many thanks to @klokare for the detail report

V1.1.0

This release contains no breaking changes!

Changes

Allow Auth client Exchange() method to take variadic oauth2.AuthCodeOption

So we can set "code_verifier" param url without needing an
HTTP request.

Courtesy of @ialbors