tests/Bounds: Fixed typos
tests/Bounds: Fixed indentation and whitespace
Bounds: Fixed comment location
Bounds: Added extendXY() method

This is a simpler variant of the extend() method, but with less overhead.
Bounds: Simplified extend() method

.. by using the new extendXY() method if the given object is LonLat or a
Point.
Merge pull request #916 from Turbo87/bounds

Added extendXY() method to Bounds class