Circularise: Updated the command to better handle mirrored selections

[micheus]

It was changed the code in order to evaluate the edge loops selection and see if they lay on the mirror face boundaries. In this case, the edge loops are handled as they were edge loops and we get the command working as it was applied in a non mirrored object. If other edge loops exists and are not laying on mirror face boundaries then the error message caused by mixed mode is displayed, just as it uses to be for non mirrored objects.

Here is a set of videos showing it working.

Let's hope for it to be approved.