In all classes:
- Read accessors return a const reference instead of a value.
- operator=() returns a const reference.
- Use '\n' instead of std::endl in all stream manipulations, when
buffer flush is not required.
- Use pre-incrementing where possible, instead of post-incrementing.
- Point3D: Destructor must be virtual (thanks cppcheck!).
- Update TODO.
- Adding WifiDevice and Mobile. AccessPoint and Mobile are sub-classes
of WifiDevice.
- Measurement: link to Mobile and AccessPoint.
- Adding CalibrationMeasurement.
- ReferencePoint: add_measurement() and operators, link to
CalibrationMeasurement (not Measurement).
- Area and Waypoint : using pointers (not references) for attribute
setting.
- Deleted class ClientInfo (replaced by Mobile).