TagLib 1.13 beta

[Urs Fleisch]

Hi TagLib users,

We plan to release version 1.13 next month. I have now tagged the
current master branch with v1.13beta. Here's the Github-generated
zip of the source at the v1.13beta tag:

https://github.com/taglib/taglib/archive/v1.13beta.zip

I would appreciate it if everyone who's tracking this list and still
actively using TagLib could give the package a try.

Thanks!
Urs