Generate IDs by hashing the station name and URL.
These IDs should be sufficiently unique.
We _may_ run into performance issues with a very large definition, but it should be fine for a sane amount of custom stations.
Revisit once we implement a custom station database.
This greatly improves loading times and takes some load off the APIs.
* Add generic directory class to also hold item count
* Radiobrowser: Get station count directly from API
* Optionally show broken stations and their count
* Remove minimum station bitrate to not filter away some listings
* Improve code wording
* Log API requests
