* **Operations:**
* Force validate all operations on execute if they haven't been before, if validation fails it will show the message error
* Add some utility functions to ease layer and mat allocation in the file
* Layer remove: Disallow to select and remove all layers
* Tool - Edit print parameters: Retract speed wasn't propagating the value to normal layers
* File formats: Better control, set and checking for null/empty thumbnails
Tiago Conceição