Propagating the recently added factors and readout properties of the HeatMapModel to the PlateViewer

I forgot to parse the data from the ScreenViewer on to the PlateViewer when I added new fields to the HeatMapModel to fix the issue #11.
fixing a small bug in the overlay popupmenu

Previously, when an empty string was added to the options list of the overlay popupmenu, the variable used to carry the options list was not seperated from the "annotations" field of the HeatMapModel. Now the list is a new instance, not modifying the content of the "annotations" field of the HeatMapModel anymore.
Adding the well annotations to the table of the WellViewer (issue #9)

... before only the readouts (well statistics) were displayed.
To get the readouts and annotations in the same order as in the configuration dialog of the node, I use the "readouts" and "annotations" fields of the HeatMapModel. To reach the data model from the WellViewer, the HeatWell, from which the WellViewer is triggered, had to provide a getter for the data model.
The Table of the WellViewer now has a tooltip for the annotation/readout values too. Before it was not necessary, having only numbers. The strings from the annotations however could exceed the column width and thus a tooltip revealing the entire string will be useful in some cases.
The readoutTable variable was refactored to wellTable.