New features in v2.83

LPD assignment validation and update capability

Previously, uploaded measurement task files for LPD (xls, xlsx files) were not validated in any way. Hence, a problem with the file was not spotted until the user tried to handle the task in the app. This was a bit tiresome as this meant that you needed to upload yet another task measurement file which was fixed. The uploaded file is now validated in order to make sure that the measurement task file can be handled by the app. In addition, the measurement task file can now be updated via "View Task" and then press the "Edit" button and upload a new measurement assignment task.