Draft: Resolve "COR: improve batch processing."

Scope

The idea is to speed up the time spend on the CoR widget when processing in 'batch' mode. It contains two points:

• no updating the GUI when receiving a new scan
• avoid doing the calculation and only work as 'serving hatch to' nabu

On the second point we should nevertheless consider the following use-cases:

• connection with other widgets like the multi-cor: some need to have the value computed to work in automatic mode
• in some cases (like building an array of CoR values found by nabu or using different version of nabu) it can be convenient to have the calculation done from tomwer.
• Nevertheless we need to keep in mind that those are more 'corner' cases at the moment. So we must keep a 'force local computation' option.

Details

screenshot