Additional colormap mode for polefigure

This implements and additional option for the polefigure widget which can be turned on/off at any given time to keep its old functionality.

If this new option is enabled:

• all printed points in the polefigure tab are now color coded
• the assigned color value depend of their intensity values
• a vertically bar is plotted next to polefigure and shows colors to which the intensity values are mappend to
• the radius of the points are adjusted to make the points for large and small alpha, beta angles equally visible

The last point is is a compromise between readability due to the area size and distance of the points with small alpha values.

In the side menu of the polefigure tab new GUI elements are implemented:

• a checkbox to turn on/off this new feature
• a groupbox with different GUI elements to adjust this new feature
• a combobox to select the used color map
• a combobox to set the number of different (color)-steps to set adjust the resolution
• two doublespinboxes to set the minimal and maximum value which is used for the colormap
• a checkbox to change the background to black (often necessary since white background gives bad contrast)
• a checkbox to enable/disable the painted grid (it can be often distracted)

Resolves issue #108 (closed) #75 (closed)

Also this implements the data inspector tool from Issue #92.