sa-axis: add the score calculation on user request only
After a discussion with @lesaint we agree that we should display the reconstructed slices ASAP.
Then score can be computed and displayed or not. But not sure the score are much meaningful. Especially when we are neat the 'real cor value'. Differences might only be noise.
For now let's split the reconstruction part and the score part for sa-axis.
Score calculation will be done on a separate thread. Once terminated the interface will be updated. If in the 'auto' mode then the COR with the higher score will be picked. If another dataset is set to the widget then current score calculation will be stopped and a 'default' COR value will be set to the previous active dataset with a warning. And previous active dataset will be moved to the next step.
Edited by payno