This avoids a linker error.

The BoundaryElementsAtPoint algorithm expects the given
point to be found in the mesh. If this fails the preconditions
for the algorithm are not fulfilled.

Distinguish two cases of empty and more than one nodes.

This is needed for polymorphism of the SearchLength alg.

Ensure that MeshNodeSearcher uses correct search length algorithm.

Especially on iterator types and 'new' allocations.

Disabled PCH on Visual Studio 2015.

Set C++ standard the right way.