I've added a new parameter "wavelengthstratificationpasses" (lengthy but not completely cryptic). Set to a power-of-two number N it will non-randomly stratify the wavelength samples for the first N-1 passes. This can improve the initial color balance, preventing the "weird color effect". From the N-th pass it continues using the regular method.
It works in a kind of hierarchical subdivision. It starts with one bin, and takes the midpoint (0.5). It then subdivides the bin into two new ones and takes those midpoints, etc. It uses the midpoints in reverse order, as I found it to be slightly better. Thus if N is 8, the offsets used for the wavelength sampling are 0.5, 0.75, 0.25, 0.875, 0.625, 0.375, 0.125.
This will introduce a slight initial bias, so if you want to disable it just set it to 0. The default value is 8.
May contain traces of nuts.