Fixed functions in pathfinding logic

I found those two inconsistencies while browsing the code. Someone familiar with the PathFinder and ObstacleCheck should have a look if I interpreted those functions correctly.
The reason to make the loop start at 1 was that distanceBetween was initialized with 0.

The only change in bahaviour of the function is this:
before: a reachable point is considered closer if it is closer than the known closest point
after: a reachable point is considered closer if it is closer than the known closest reachable point

The old behaviour seemed quite odd to me. It is only reasonable if you assume that the points in the Pathgrid are ordered in the distance to the destination somehow.