Convenient GUI for editing imat_shp data attributes.
g=edit_attributes(f)
EDIT_ATTRIUBTES is a convenience Graphical User Interface for editing imat_shp attributes. Most attributes are editable. The GUI groups related attributes for easy editing.
The input argument to EDIT_ATTRIBUTES is an imat_shp. It can be an array of functions. The output G is an imat_shp containing the modified imat_shp. If the user clicks on 'Cancel', then g=-1 is returned.