complete help dataset properties

[HGarre]

Integrate a better description of properties esp. to upload new datasets from excel files:

• quality levels: 0: raw, 1: formal checked, 2: quality checked, 3: calibrated, 4: derived value (what is difference between formal and quality checked?)
• access levels: : public dataset, 1: only known users / project members, 2: only users with editing privileges, 3: only employees / data managers, 4: only administrators
• all properties must be filled with standard values for upload (until "datasets creation empty columns" is solved)
• ID is not a property, delete this column when uploading datasets from excel