As of 03/04/2019, Development on Tilemancer has officially been stopped. I appreciate all the support and feedback, and even though Tilemancer might have been useful, I don't feel the concept was matured enough.
Tilemancer spawned the development of a spiritual successor called Tilesetter, which is currently in development and has a slightly different focus than the first, taking into consideration aspects in which Tilemancer failed. The successor works with complete tilesets in contrast to single tiles, may incorporate more 'authentic' procedural generation in future versions, and is something i'm very excited about!
For Tilemancer, you can find it's source code here: https://github.com/Ledgamedev/Tilemancer
It was a good run. Thank you all for the support and keep an eye out for the new Tilesetter!