Tests for stereo and atom. New object - 'elementary lattice structure'. Added: matrix_layout.rb, node.rb and atom_spec.rb. Modifyed: atom.rb, specie.rb, stereo.rb, stereo_spec.rb, diamond.rb.
Finished tests.
test - bond_spec.rb. Need to move functions to MatrixLayout.
Functions of extending moved to MatrixLayout. Tests for MatrixLayout.