updated release notes

docs/docs/release_notes.xml

@@ -32,23 +32,22 @@ New Features:
       - Added an overload of sparse_matrix_vector_multiply() that multiplies a dense matrix
         with a sparse vector.
       - Added the find_affine_transform() routine.
-      - Made toMat() work with matrix object in addition to array2d style images.
-      - Added the mat() function. It rolls the array_to_matrix(), vector_to_matrix(),
+      - Made toMat() work with the matrix object in addition to array2d style images.
+      - Added the mat() function.  It combines the array_to_matrix(), vector_to_matrix(),
         pointer_to_column_vector(), and pointer_to_matrix() methods all into one convenient
-        interface. Also made stddev() slightly more general. This change also deprecates the
-        previous matrix conversion functions.  mat() also works for Armadillo and Eigen matrices.
+        interface.   mat() also works for Armadillo and Eigen matrices.
       - Added STL style begin() and end() methods to matrix and matrix_exp.
    - Graphical User Interface Tools
       - Added draw_solid_convex_polygon()
       - Added an overload of draw_image() that's useful for drawing images and doing
         interpolation at the same time.
-      - Added on_view_changed() callback to zoomable_region and scrollable_region gui widgets.
+      - Added the on_view_changed() callback to zoomable_region and scrollable_region widgets.
    - Added parse_trees_to_string() and parse_trees_to_string_tagged()
    - Added lambda function support to the timeout object.
-   - Added the vectorstream object.
+   - Added the vectorstream object
    - Added the parse_xml() routines
-   - Added a group name feature to the command line parser. Now it is possible to make
-     print_options() print related options so that they are grouped together.
+   - Added a group name feature to the command line parser.  Now it is possible to make
+     print_options() print related options in named groups. 
    - Added the following new hashing functions: murmur_hash3_128bit_3(),
      murmur_hash3_2(), murmur_hash3_3(), uniform_random_hash(), gaussian_random_hash() 
      as well as hash() overloads for uint32, uint64, and std::pair.
@@ -57,20 +56,18 @@ Non-Backwards Compatible Changes:
    - Made the svm_c_linear_trainer use the risk gap to decide when to stop.  This was done
      because it is how all the other OCA based SVM tools in dlib decide when to stop.  
      However, it might cause the outputs to be slightly different in this version of dlib.  
-   - Switched the windows implementation of dlib::mutex to use a CRITICAL_SECTION instead
-     of a "mutex" (i.e. the thing made by CreateMutex()) since a critical section does the
-     same thing but faster.  Also changed the spec for mutex::unlock() to say that it is
-     illegal for a thread to unlock a dlib::mutex it doesn't own. This is technically a
-     non-backwards compatible change to the API but it has always been implemented in a way
-     that didn't allow this kind of double unlock() on non-Windows platforms. Additionally,
-     the recent change to the dlib::mutex implementation on windows also no longer allows
-     this kind of double unlock.
+   - It is now illegal to call unlock() on a mutex when the mutex is not owned by the
+     calling thread.  The most likely reason for doing this was to unlock early in an area
+     locked by an auto_mutex.  Old code that does this can be fixed by calling auto_mutex's
+     unlock() function instead.  
    - Removed the structural_assignment_trainer::learns_nonnegative_weights() routine 
      and moved its functionality into the feature extraction interface used by this object. 
 
 Bug fixes:
    - Fixed a bug in find_max_factor_graph_nmplp() which caused it to not work properly on
      some compilers.
+   - Fixed a bug pointed out by Joel Nelson in the version of md5() that took an istream.
+     The bug caused the function to crash on strings longer than 56 characters.
 
 Other:
    - dlib now has an excellent new logo thanks to Yasser Asmi.