Quadtree: prevent infinite insert/refine recursion

[yakra]

aln.starrd.wpt was specifically designed to:

• look pretty in wptedit, and
• break the WaypointQuadtree insert/refine process.

Running it thru siteupdate.py, I get a ton of

 File "./siteupdate.py", line 72, in refine
self.insert(p)
File "./siteupdate.py", line 92, in insert
self.ne_child.insert(w)
File "./siteupdate.py", line 81, in insert
self.refine()

scrolling off the top of my terminal window, until finally,

 File "./siteupdate.py", line 65, in refine
self.nw_child = WaypointQuadtree(self.mid_lat,self.min_lng,self.max_lat,self.mid_lng)
RecursionError: maximum recursion depth exceeded
[0.3] Finding unprocessed wpt files.

followed by some more normal-looking output, then

[2.4] Performing data checks...Traceback (most recent call last):
File "./siteupdate.py", line 2990, in <module>
if r.point_list[0].is_hidden:
IndexError: list index out of range

I've modified the WaypointQuadtree so that each node can contain up to 50 unique locations, rather than 50 points.

[jteresco]

I like this. Ready to merge and go to production?

[yakra]

I believe so.

Just for fun:
As of HighwayData@a46d6d9,
Total number of Quadtree nodes: 62237 -> 42725
Number of bottom-level nodes, containing waypoints: 46678 -> 32044

[yakra]

Oops, I goofed on a couple changes to is_valid, and didn't notice because the only call to it is commented out. Will add another commit shortly.

[yakra]

I believe again that it's ready.

[yakra]

@jteresco, does any info from/or about the quadtree get put into the DB, into the .sql file?
Anything to watch out for there?

[jteresco]

No, it's gone when the site update process ends. Entirely to make searches by coordinates a lot more efficient.