Made the sample_pair have a default distance of infinity instead of

the max floating point value.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403658

dlib/manifold_regularization/sample_pair.h

@@ -20,7 +20,7 @@ namespace dlib
             _index1(0),
             _index2(0)
         {
-            _distance = std::numeric_limits<float>::max();
+            _distance = std::numeric_limits<float>::infinity();
         }
 
         sample_pair (