Relational/Equality Operators
The next set of operators we will examine are the relational
and equality operators
These should be overloaded as non-members as either the
first or second operands could be a non-class object:  string
< literal,  literal < string,  string < string
Neither operand is modified, so all class objects should be
passed as constant references.
The residual value should be a bool, however an int will
also suffice, returned by value.
If overloaded as a member -- make sure to specify them as a const
member, for the same reasons as discussed earlier.