ISSUE#83

Fix up database creation and add in new tables/delete old tables.
ISSUE#83

Add new model elements for conditions and params. Move some params to
conditions to further describe the object. Rework the layout to move
basic functionality into DataItem.
ISSUE#83

Rework DataItem into a base class used by DataFile and DataParam (and
soon to be used by DataSet).
Rework inheritance.
ISSUE#83
Fixup task to work with changed data model