Cover art support

- implement database scheme
- search for embedded cover
- search for cover in track directory
- save covers in disk cache
- search for covers in disk cache
- minimal ui (display covers in lower left corner)
- handle existing users
- LRU cache
<https://github.com/daschuer>

 > @daschuer <https://github.com/daschuer>, if it's also fine for you...
c7d07c9
<https://github.com/mixxxdj/mixxx/commit/c7d07c98dacab15380dfa58ec1e71da2db520416>

Yes, cool, I did not know that indexOf(QRegExp) works.

It would be cool if you can put a comment above each return branch like
this:

// Only a single picture in folder, return it.




<https://github.com/mixxxdj/mixxx/commit/c7d07c98dacab15380dfa58ec1e71da2db520416>


2014-06-25 2:19 GMT+02:00 Marcos Cardinot <notifications@github.com>:

> In src/library/coverartcache.cpp:
>
> > +    QImage image = QImage(coverInfo.currentCoverLocation);
> > +    if (!image.isNull()) {
> > +        res.coverLocationFound = coverInfo.currentCoverLocation;
> > +        res.img = image;
> > +        return res;
> > +    }
> > +    image = QImage(coverInfo.defaultCoverLocation);
> > +    if (!image.isNull()) {
> > +        res.coverLocationFound = coverInfo.defaultCoverLocation;
> > +        res.img = image;
> > +        return res;
> > +    }
> > +
> > +    // Looking for embedded cover art and for cover stored in track diretory.
> > +    //
> > +    QImage newImage = searchEmbeddedCover(coverInfo.trackLocation);
>
>  Do you think that we should reorder it?
>
> yes always prefer metadata. Lets just make this a design rule. This is
> also the intended way to save a cover per track in every other application
> that I know. Plus id3v2 was made exactly for that purpose.
>
> @daschuer <https://github.com/daschuer>, if it's also fine for you...
> c7d07c9
> <https://github.com/mixxxdj/mixxx/commit/c7d07c98dacab15380dfa58ec1e71da2db520416>
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/mixxxdj/mixxx/pull/278/files#r14163537>.
>