simpler Measurement classes based on namedtuple
Fully implemented new Measurement classes as subclasses of
namedtuple. #112.

Also implemented all tests for new measurement classes
Fully implemented new Measurement classes as subclasses of
namedtuple. #122.

Also implemented all tests for new measurement classes
Fully implemented new Measurement classes as subclasses of
namedtuple. #122.

Also implemented all tests for new measurement classes