The developer has now posted:
I uploaded all the source-code of Windows Phone Internals to Github. I also created some tooling which helped me developing Windows Phone Internals. I will upload this to Github too somewhere soon. I will still do some development, but don't have much time for it lately. So I hope other developers and hackers can contribute too. If Microsoft will ever release a Surface phone, I will have a new challenge and work on that. Maybe I will try to hack an iPhone in the meantime, LOL. The source of Windows Phone Internals can be found here: https://github.com/ReneLergner/WPinternals
Back when this project started, there was hope of Lumias being unlocked and then flashed beyond the current 'feature2_rs3' OS branches. Which should, in theory, be possible, because of the shared Windows 10 code with the Desktop. But we haven't currently seen any builds which are usable in a mainstream context.
Still, who knows? If you're a good coder and looking for a rainy day project then why not get involved?