Better support for fetching stickers from MPD

[multani]

MPDClient now parses the output of MPD and provide a more convenient way of accessing stickers.

Otherwise, clients have to parse the output by hand, which is not very convenient...

[Mic92]

I agree with you. This is right and the better way.
But I have to drop the "drop-in replacement" label from my library.
And we have to document this api break.

[multani]

Well.

As I see it, the lib is quite stable at the moment, it's up-to-date with the current MPD, and gets most "base" features that it can have (Python 3, extensibility, full command set (even if it doesn't handle everything the best it could, as for the stickers), etc.)
But, this is not yet v1.0, and upstream repository looks as dead as a dry slug smashed by car. So, I would say: assume the fork (drop-in until v0.4.x), and break the API if it's for greater good.

But well, you are the maintainer :)

[Mic92]

We just need, something like a porting guide, which shows the api difference.
The origin project have some examples, which should be ported too.

[multani]

I'll take care of this.

[multani]

And hop!
As always, both code and doc are subject to review for improvements!