Fix containing face not being found

[ayden175]

MeshMap::searchContainingFace() only checked the faces directly adjacent to the single nearest vertex found via getNearestVertexHandle(). For the (irregular) mesh that I was using, this sometimes caused the problem that the function would fail to find the containing face, as it was not connected to the nearest vertex. Here is a visualization of the specific issue I had:

To solve this, I replaced the single-ring face check with a best-first search:

1. Start from the nearest vertex v as before
2. Instead of only checking faces of v, expand outward via getNeighboursOfVertex(), visiting the next-closest unvisited vertex to the query point first
3. Check all faces touching each visited vertex, tracking the best (lowest-distance) containing face found so far
4. Stop expanding once the frontier's minimum distance exceeds max_dist

Also potentially related to #31

[amock]

At first glance, doing a small limited search is definitely an optimization over just returning an error. I'll have a look at it soon.

[amock]

Nice addition! I tested it with the tutorials and from my point of view it only improve things. Note that the optimal solution to this problem is sketched in #104 and will probably replace this one as soon as it is implemented.