adding a test class for the ColorGradientDialog

removing the quick testing method (main) in the ColorGradientDialog.
rendering certain fields of the HeatMapViewerTest public in order to be able to reuse them.
fix for the thumb adding error (issue #5)

adding a condition to check if the bound (thumb) to add to the color gradient is on the color scale.
modifying the checks for the bounds in the rendering. If the left bound was outside the color scale, the right bound has to be corrected.
deactivating the right click functionality of the ColorGradientSlider (issue #7)

the contextual menu evoked by the right click had some quirks; If the thumb was not hit exactly in the middle it would move a bit before the contextual menu (color menu) would open. Since the contextual menu does not offer the ability to cancel the selection, it's better to choose the colors with the dialog (evoked by double clicking on the thumb).
avoiding overlaping of the labels

adding the bounds of the reference population to the tooltip of the population panel.
adding a reference group name
recompiled the GradientSlider

commented out the code for the contextual color selector.
pimping up the GradientSliderDialog (issue #7)

-adding a text area indicating the cursor position on the color gradient
-adding an options panel to select the descriptor type (mean, median, SD, MAD) as well as the deviation factor.
-changing the way the mean and the bounds of the reference groups are displayed. The new methods avoids overlapping of labels by leaving the bounds out if they touch the mean. The complete bounds still are indicated in the tooltip.

fixing a bug in the calculation of the population descriptors. The values were continuously added so the first descriptors were right, but the second would calculate the descriptors for the first and the second group, the third for the first, second and third and so on.
fixing a typo
Adding some fields to the node serialization routine

once the view was loaded, it had forgotten about the readouts, factors and ref. populations. This is fixed now.