Fix cloning not-opacity scalar keyframe channels
Before this commit, duplicating a layer with keyframe channels that weren't specifically an opacity keyframe channel resulted in loss of those channels. This commit provides an universal solution for all scalar kyeframe channels available. At this point there is no way of making a scalar keyframe channel except for opacity keyframes unless you make a change in the code and compile it yourself (see animation_docker.cpp, line 508), so there is/should be no change in behaviour for users. However if you enable animated transform masks, this become crucial for both duplicating layers and saving the file with keyframes (it doesn't work for now, but without this commit it most probably wouldn't).
Showing with 22 additions and 3 deletions