size().  This way, linearly_independent_subset_finder objects can be used in many
   templated functions which expect objects which look like arrays.
 - Generalized the kernel_matrix() function slightly so that it can work with anything
   that looks like an array.  This now includes linearly_independent_subset_finder objects.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403893