Stock move sorting not usefull after reception

Stock move sorting is defined as 'date_expected desc, id' . This is useful as long as the items did not arrive yet. At this stage the date field is not used/empty.

At delivery the date field is set as the real reception date. After reception it is IMHO no longer interesting to have the sorting driven by the expected date but from the received date.

In order not to loose the original expected date, thus still allowing to check if a delivery was in time etc, I propose to update the date from the date_expected as long as the move is not in state done and to define sorting as 'date_expected desc, id'. Additionally the date field is set to readonly (in views) in order to avoid that it is changed manually.