Library update

[Sylvain Bougerel]

Hi all,

I just pushed the latest version of libkdtree to the server.
Next, I'll be focusing on providing automated tarballs for the library.

Below is the commit message:

This release features removal of all the warnings that are yield by the
compiler when using the following flags:
 -Wall -pedantic -ansi
Do not hesitate to suggest any flags for additional code checking.

This release also features numerous of enhancements by Paul Harris:
* const kdtrees can be searched
* find_nearest_if() enforce validation of a predicate
* visit_within_range() walk the tree and calls Visitor::operator() on template
  argument <Visitor> for each node within the range
* find_exact() matches an kdtree::value_type by location and by calling
  kdtree::value_type::operator==() (in case two different items have the same
  location find_exact() will not return the wrong item)
* erase_exact() is to erase() what find_exact() is to find()
* check_tree() and num_dist_calcs for debugging purpose
plus additional improvements on erase and region intersection


Happy Halloween,

- Sylvain