Changed the add_probability() method of joint_probability_table so

it does a saturating add rather than a normal add.  This ensures the
probability value stays exactly <= 1.  Previously, floating point
rounding error could cause it to be slightly above 1 and would therefore
cause some asserts to misfire during debugging mode.

dlib/bayes_utils/bayes_utils.h

@@ -333,6 +333,8 @@ namespace dlib
             if (table.is_in_domain(a))
             {
                 table[a] += p;
+                if (table[a] > 1.0)
+                    table[a] = 1.0;
             }
             else
             {

dlib/bayes_utils/bayes_utils_abstract.h

@@ -294,7 +294,8 @@ namespace dlib
                     - #size() == size() + 1
                     - #probability(a) == p
                 - else
-                    - #probability(a) == probability(a) + p
+                    - #probability(a) == min(probability(a) + p, 1.0)
+                      (i.e. does a saturating add)
                 - #has_entry_for(a) == true
         !*/