Improve Astorequalpartsshowdiff

[ChristianBlei]

If two parts are "different in geometry", the result of this command is not specific enought. Usually this message means that there are differences in features.

So the parts should be shown with their features and the featues that are not identical should get unique colors to be able to identify them and correct easily what is not identical. Also a specific listing of the differences between features show be part of the list of differences.

Christian Blei.