Improved FFT denoise

[Ammoniteii]

The FFT denoise tool is pretty cool ,but could be improved in a number of ways in my opinion. 

Firstly - allow the FFT Denoise panel to go full screen, it can be very annoying to work in a limited window, yes there is zoom, but allow us to look at the picture better by allowing the ability to full screen to tool window. 

Secondly - allow a history panel within the tool - sometimes i need to go back and do more denoising, and the previous edits are there, but i cannot change or undo any edits made to the "denoise map"

Thirdly - Allow for a layers option - similarly to above, allow for "denoise layers" - that way i can change the severity of a group of edits with opacity, turn them off to view the previous state, or build up denoise based on colour intensity etc. 

Finally - Improve the performance of the window - it can be very sluggish to react, meaning that you can over or under draw on large files, i realise this may be a pain but perhaps if layers were implemented - you would draw on the layaer, then "bake" an "unbake" the layer to apply / remove it from the original image, this would still allow for a live preview of actively baked layers