to data2D.crop_data
center: final position of data center (0,0) in x and y data coordinates, 
if 2 element, center data coordinates, if 3 elements, center also data.
This means e.g. that data are first cropped (or cleaned of invalid data) than centered. This means that the value puts in the provided coordinate(s) the center of points after cropping operations.
unexpected parameters passed to register_data are ignored (<a href="#id3"><span class="problematic" id="id4">*</span></a>args and <a href="#id5"><spa