Implemented copy constructor
Renamed "dereference" to more-common "deref"
Initial implementation of == and != (not working)
Completed implementation of == and != for rows
Merge branch 'feature/equals'
Initial implementation of comparison operators
Added unit tests for row comparisons
Merge branch 'feature/comparison-operators'
Implemented row multiplication
Implemented row division
Python 2 support for row division
Added simple unit tests for multiplication and division
Tidied arithmetic operator implementation
Removed requirement for both operands of arithmetic operators to be Row objects

We can assume at least one object must be a Row as the method has been called.
Trying to convert both means we can support string inputs too.
Made same improvements to comparison operators
Implemented remaining arithmetic operator unit tests
Merge branch 'feature/arithmetic-operators'