Missing "this->" in evaluateError() in BearingRangeFactor.h

[daanwildiers]

When using the
Vector evaluateError(const A1& a1, const A2& a2, boost::optional<Matrix&> H1 = boost::none, boost::optional<Matrix&> H2 = boost::none) const
function in BearingRangeFactor.h, it is not possible to compile using catkin build in a catkin workspace.
On line 82 in const Vector error = unwhitenedError({{keys[0], genericValue(a1)}, {keys[1], genericValue(a2)}}, Hs);
there is a missing this-> before unwhitenedError(. When prepending this-> the code compiles perfectly.
So it should be nice if this-> is added before unwhitenedError( on Github.

[dellaert]

I assume you have a fork, can you PR this change to develop?