v2 Re-implement the dobj class

[ZogopZ]

Use icoscp_core to completely rewrite the Dobj class (following the old Dobj class return types) for version 2 of icoscp. The following projerties/methods are to be re-implemented:

• [ ] Dobj.info
• [ ] Dobj.meta
• [ ] Dobj.citation
• [ ] Dobj.get_citation(format)
• [ ] Dobj.licence
• [ ] Dobj.previous
• [ ] Dobj.next
• [ ] Dobj.colNames
• [ ] Dobj.variables
• [ ] Dobj.data
• [ ] Dobj.get(variables)
• [ ] Dobj.getColumns(variables)
• [ ] Dobj.dateTimeConvert = True
• [ ] Dobj.dobj = PID
• [ ] Dobj.id = PID
• [ ] Dobj.valid
• [ ] Dobj.lat
• [ ] Dobj.lon
• [ ] Dobj.elevation
• [ ] Dobj.alt
• [ ] Dobj.station
• [ ] Dobj.size()