Several changes in Kruskal alg.
- Input object interface was changed to an STL compatible one.
- template parameters of class KruskalPairVec has been simplified.
- (the most of) the names meet the naming conventions.
- a lot of (but still not enough) documentation has been added.
- class KruskalMapVec has been commented out.

 #include "test_tools.h"

 int main() 

 {

   check(false, "Don't panic. Failing is the right behaviour.");

   return 0;

 }