Switching from magnitude spinboxes to slider widgets in the Configure window, for controlling the label density of asteroids and stars.We used to provide a magnitude limit, and all objects brighter than the limit would be labeled.

We now have a more advanced labeler that avoids overlapping text, so a UI control that controls the relative density of labels is more appropriate.I updated all code that interacted with the old controls.

The new parameters are named:
Options::starLabelDensity()
Options::asteroidLabelDensity()

Everything seems to be working as expected.I wasn't sure what range of values would be useful, so right now the range is 0 to 20. This can be changed in the code itself, or in the *.ui files.