enh: added warnings when using construct for 1-orbital systems
enh: added warnings when using construct for 1-orbital systems

In case the user accidentially have two atoms lying ontop of
each other sisl will now print warnings.

Signed-off-by: Nick Papior <81a73bca3d342ffee33d7cf845fdbf77b6553831@gmail.com>

zerothi/sisl,zerothi/sisl