VocabLib/include/VocabTree.h
* Added directive controlled by the compilation cycle for printing
messages to standard output.
* In method compareEqual, changed method signature to operate over
pointers rather than references.
* In method compareEqual, re-implemented method I was using wrong
algorithm for traversing the tree and checking the nodes centers.

VocabLib/tests/Makefile
* Added directive for enabling messages output from libvocab, but
commented for now.