Create animated PNGs (APNG)

Safari 8 [supports](http://caniuse.com/#feat=apng) the [unofficial APNG extension](https://wiki.mozilla.org/APNG_Specification) to the standardized PNG format. Most popular image editors (on any platform) do not support APNG (yet). Plugins are mostly available for Windows software only. Searching Macupdate returned nil as well. How can I generate an APNG from a series of still PNGs (not from a video file) on OS X? (Although I understand the file structure, I’m hesitant to do it manually.)