Made the spec specifically say that new samples get appended to the end

of the linearly_independent_subset_finder.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403619

dlib/svm/linearly_independent_subset_finder_abstract.h

@@ -119,6 +119,7 @@ namespace dlib
             ensures
                 - if (x is linearly independent of the vectors already in this object) then
                     - adds x into the dictionary
+                    - (*this)[#dictionary_size()-1] == x
                     - returns true
                     - if (dictionary_size() < max_dictionary_size()) then
                         - #dictionary_size() == dictionary_size() + 1