Adding attributes to the class Atom describing the number of lone
electron pairs along with function to manipulate and request their
values.
Removed a code section responsible for saturating the input adjacency
lists with hydrogen atoms from the function fromAdjacencyList requiring
that the input adjacency list have include already all hydrogen atoms.
Added a new code section calculating and storing the number of lone
electron pairs and electric charges for each atom which is possible only
if the adjacency list contains all hydrogen atoms.