Prevented some spatial relation artifacts.

I.e. polys are found inside points or linestrings, just in case these aren't
already rejected by preceding bbox queries.
Inverted rejection of dim-0/dim-1 objects from 'covers'.

MultiPoints have been missing anyway and the indexOf() condition was wrong and
this wouldn't have worked at all.
Inverted and rewrote point processing order.

Now they look similar, which is neat. Also I don't have to access points.length
in every iteration (although I assume that even SpiderMonkey should be able to
optimize something like that). Calling Array.pop() certainly might decrease
performance.