Test point in element

Introduces extension of the Element-interface by adding a method ```bool isPntInElement(GeoLib::Point const& pnt)``` that will return true if the point is located either inside or on the boundary of the element and false otherwise.
For line-elements it tests if the point is located on that line, for 2D elements the point needs to be coplanar with the element nodes and located inside the 2D element.

This introduces a little redundancy to the current Face-interface (i.e. Tri's and Quad's) where already a method ```isPntInside(pnt, eps)``` exists which basically does the same but allows to specify an additional epsilon. Currently, I have left this method as it is. Should I remove it?
originally I only had a default value in the base class but the derived classes didn't make use of that. Lars suggested that if methods are re-implemented in derived classes, default values are not carried over (that is why I need to include the default value in the derived classes) and since the method in the base class is pure virtual a default value isn't required as there is no implementation.
I would like to keep the default value because it allows maximum flexibility when doing mesh verification things (I think in most cases I can actually use the default value). Weather it's there or not has no impact on how you use eps-values during simulation, you can still keep a consistent eps value for your calculations.