Slow compilation time in a big project. What branch contains Incremental Compilation?

[Hlaaftana]

To be clear incremental compilation is in normal Nim since 1.6, enabled with 
--incremental:on. I don't know if it's in a usable state but if you were going 
to test using it you should probably test the development version as I would 
guess the bulk of the progress on incremental compilation would be after 1.6.