== (zmatrix) #=> true/false
Compares two z-matrices. Both the topology and the coordinates
must be identical.
same_topology?(zmatrix) # => true/false
Compares topology of two z-matrices. The topology is considered
identical if the z-matrices contain the same atoms in the same order,
and all coordinates are defined identicaly. The only thing that
can be different are values of the coordinates.