Add APCBG as authority, add `apcbg-bul-cyrl-latn-1995` system and link adopting systems

[calconnect-ci]

In GitLab by @ronaldtse on Feb 27, 2020, 19:38

APCBG "Antarctic Place-names Commission of Bulgaria" is the first authority that adopted the Streamlined System for Romanization of Bulgarian (Lyubomir's system, can't believe I forgot).

The system has been adopted by:

• Bulgarian Parliament (BGNA in authority code)
• UNGEGN
• BGN/PCGN

These systems should link back and inherit from the APCBG system.

Source document: http://www.apcbg.org/Toponymic-Guidelines.htm

Compiled by Dr. Lyubomir Ivanov
Institute of Mathematics and Informatics
Bulgarian Academy of Sciences

[calconnect-ci]

In GitLab by @ronaldtse on Feb 27, 2020, 21:30

closed via commit b0802788b648b39518e7f4bf7c27184003f3140e