Superfluous empty rows in parameter and entity alternative tables

[soininen]

It is possible to add empty rows to Parameter value, Parameter definition and Entity alternative tables just by double-clicking all the cells but not entering any data. When the last cell has been "edited" this way, Database editor seems to think that the user actually entered some data and adds a new empty row to the tables. Note, that this works only when no cell, including entity_class_name is prefilled.