TODO:
* test 7e7c0e4dd08b4a15d4ce251e64ca267bb2d9e25e on windows.
* Remove the usage of KDialog, swith to QDialog. Following dialogs are affected:
** DatabaseManagerDialog
** ImportDialog
** FITSHeaderEditNewKeywordDialog
** FITSHeaderEditDialog
** FITSHeaderEditAddUnitDialog
** GridDialog
** ExportWorksheetDialog
** DropValuesDialog
** EquidistantValuesDialog
** ExportSpreadsheetDialog
** FunctionValuesDialog
** MatrixFunctionDialog
** HistoryDialog