Example data:
2016-12-21 09:27:53;629
2016-12-21 09:28:53;642
2016-12-21 09:29:53;656
...
see https://bugs.kde.org/show_bug.cgi?id=374871
Tasks:
* Preview in import dialog
* import into spreadsheet/matrix (?): needs additional data type?
* plot data in datetime format : needs additional tick label format?
Ideas:
* Use QDateTime
* convert datetime internally into uint (toTime_t())