Update to 3GPP TS 29.061 V15.5.0 (2018-12) Add AVPs: - TWAN-Identifier, OctetString, code 29, section 16.4.7 - 3GPP-User-Location-Info-Time, OctetString, code 30, section 16.4.7 - 3GPP-Secondary-RAT-Usage, OctetString, code 31, section 16.4.7 - MBMS-Access-Indicator, Enumerated, code 923, section 20.5a.1 - MBMS-GW-SSM-IP-Address, OctetString, code 924, section 20.5a.2 - MBMS-GW-SSM-IPv6-Address, OctetString, code 925, section 20.5a.3 - MBMS-BMSC-SSM-UDP-Port, OctetString, code 926, section 20.5a.4 - MBMS-GW-UDP-Port, OctetString, code 927, section 20.5a.5 - MBMS-GW-UDP-Port-Indicator, Enumerated, code 928, section 20.5a.6 - MBMS-Data-Transfer-Start, Unsigned64, code 929, section 20.5a.7 - MBMS-Data-Transfer-Stop, Unsigned64, code 930, section 20.5a.8 - MBMS-Flag, Unsigned32, code 931, section 20.5a.9 - Restart-Counter, Unsigned32, code 932, section 20.5a.10 - Diagnostic-Info, Unsigned32, code 933, section 20.5a.11 - MBMS-Cell-List, OctetString, code 934, section 20.5a.12 Update notes and comments to reflect current style.

The digested changelog can be found under:
 contrib/debian/changelog
 
You can also find the exhaustive list of change using mercurial history, 
or at the following URL: http://www.freediameter.net/hg/freeDiameter/shortlog