Remove all using directives for STL namespace and members

Made all STL usages explicit to be able automatically find all usages of
particular class or function.

modules/imgproc/src/segmentation.cpp

@@ -64,7 +64,7 @@ struct WSQueue
 
 
 static int
-allocWSNodes( vector<WSNode>& storage )
+allocWSNodes( std::vector<WSNode>& storage )
 {
     int sz = (int)storage.size();
     int newsz = MAX(128, sz*3/2);
@@ -93,7 +93,7 @@ void cv::watershed( InputArray _src, InputOutputArray _markers )
     Mat src = _src.getMat(), dst = _markers.getMat();
     Size size = src.size();
 
-    vector<WSNode> storage;
+    std::vector<WSNode> storage;
     int free_node = 0, node;
     WSQueue q[NQ];
     int active_queue;