Added a function to determine how many threads a structural_svm_problem_threaded

object is going to use.

dlib/svm/structural_svm_problem_threaded.h

@@ -34,6 +34,9 @@ namespace dlib
             tp(num_threads)
         {}
 
+        unsigned long get_num_threads (
+        ) const { return tp.num_threads_in_pool(); }
+
     private:
 
         struct binder

dlib/svm/structural_svm_problem_threaded_abstract.h

@@ -40,8 +40,15 @@ namespace dlib
         /*!
             ensures
                 - this object is properly initialized
-                - This object will use num_threads threads at a time to call the 
-                  separation_oracle() function.  
+                - #get_num_threads() == num_threads
+        !*/
+
+        unsigned long get_num_threads (
+        ) const; 
+        /*!
+            ensures
+                - Returns the number of threads which will be used to make concurrent
+                  calls to the separation_oracle() function.
         !*/
 
     };