Loading: Simplify 'multipath' option for decadal loading module
Right now, the decadal loading module uses a complex work-around in order to be able to load dcppA-hindcast and dcppB-forecast years together in the same array, and then adjust the metadata accordingly.
I have found a good Start() call that should work for this case (and possibly all cases?), see: startR!236 and startR#202 (comment 294583)
The next step would be trying to apply this to the decadal loading module and getting rid of the unnecessary workarounds. This would also simplify the usage of Compute().