After having another close look, I must correct myself: Only now I noticed the changed done on the SVN repo here between 2014 and 2018 - seems to be a similar amount of changes to those that happened on github and never made their way back into the main subversion repo. I guess, it would be worth consolidating these changes.
The main developer abandoned the project a long time ago, but the quality is still so good that it is worth preserving. Back in 2014, I carefully revised and merged all the free-floating forks of the BSD-licensed version 2.4 into one git repository: https://github.com/NNemec/antigrain At that time, I fixed all compiler warnings and various issues to bring the library to a state where I could successfully use it in a commercial product. To my knowledge, that merge still is the highest-quality fork...