I'm glad you like the theme.
For an icon set, the "source" is usually the set itself. I made these icons by using various methods with Inkscape and Krita. Most of them are SVG-based but, most of the time, I didn't just exported PNG from SVG. The SVG files are a such mess that I prefer to focus on creating icons with high quality rather that doing the boring task of organizing their SVG origins.
That said, a simple Makefile and a debian folder could be created to package the whole set into a deb package, and a similar thing could be done for rpm too. That's rather a distro job though.
Thank you for telling me about "apps/application-x-clementine"! I'll make a symlink for it with the next update. For now, you could do that with this command in all apps folders and then recreate the icon cache:
ln -s clementine.png application-x-clementine.png
The forward/backward button issue doesn't happen here. The versions of Konqueror, Dolphin and KDE are all 4.11.3 here.