a van Emde Boas tree

[Alex]

Hi all,
my van Emde Boas tree finally reached an announceable state, at 
version 0.12.0.

It operates on a closed universe, defined on construction.

After that, the tree operates on unique key up to a certain 
capacity, which is at least as large as the universe size.

All operations including insertion, removing, look up and next 
neighbor search are O(log(log(U)). min and max lookup are O(1).

Some graphics are included on the front page for performance 
comparison with existent libraries.

I relicensed the package to BSL-1.0 and moved it on github, so 
the documentation should work properly now.

All tickets are welcome of course and will be managed in my spare 
time.