Release v1.5.1 on 2021-02-24.

1. 2fe50ac doxygen: enable cross referencing everywhere by Neels Hofmeyr · 5 years ago
2. 95efc69 doxygen: config: one enum val per line by Neels Hofmeyr · 7 years ago
3. 87e4550 doxygen: enable AUTOBRIEF, drop \brief by Neels Hofmeyr · 7 years ago
4. 5181647 doxygen: include all undocumented items in the API doc by Neels Hofmeyr · 7 years ago
5. c663678 Add doxygen documentation to libosmocoding by Harald Welte · 7 years ago
6. 3262f82 libosmocoding: migrate transcoding routines from OsmoBTS by Vadim Yanitskiy · 8 years ago