First crack at merging layer images. I think it only works for normal blended layers.
Use layer mask channel
Merge branch 'master' into image_merging
Fix specs
Get ready for color composing
Implement multiply blend mode
Implement screen blend mode
Implement overlay
Add difference blend mode
Added darken and lighten
Comment note
Redo of blend modes
Soft light blend mode
hard light
Cleanup
Gah
Vivid light
Linear light and typo fix
Pin light
Hard mix