Feature suggestion: Add "divide" layer mode

[krakowiakwojciech]

Strongly suggest to add "divide" layer mode, very useful for different operation. Attachment from photoshop where you can see applayed picked white color sample from X-rite (sligly blue), used that color to fill layer on divide mode and compesate that with grey layer on multiple. Can't do similar thing in Affinity photo. Especialy with bath module