fixing build of 2.4 branch with VC12 (aka 2013)

(master branch was fixed before, no need to merge this to master!)
- disable openexr (numerous undefined std::min & std::max)
- workaround for two compilator bugs

modules/features2d/src/features2d_init.cpp

@@ -181,7 +181,7 @@ CV_INIT_ALGORITHM(DenseFeatureDetector, "Feature2D.Dense",
                   obj.info()->addParam(obj, "varyImgBoundWithScale", obj.varyImgBoundWithScale));
 
 CV_INIT_ALGORITHM(GridAdaptedFeatureDetector, "Feature2D.Grid",
-                  obj.info()->addParam(obj, "detector", obj.detector);
+                  obj.info()->addParam(obj, "detector", (Ptr<Algorithm>&)obj.detector);
                   obj.info()->addParam(obj, "maxTotalKeypoints", obj.maxTotalKeypoints);
                   obj.info()->addParam(obj, "gridRows", obj.gridRows);
                   obj.info()->addParam(obj, "gridCols", obj.gridCols));

modules/features2d/src/orb.cpp

@@ -138,13 +138,16 @@ static void computeOrbDescriptor(const KeyPoint& kpt,
     const uchar* center = &img.at<uchar>(cvRound(kpt.pt.y), cvRound(kpt.pt.x));
     int step = (int)img.step;
 
-#if 1
-    #define GET_VALUE(idx) \
-        center[cvRound(pattern[idx].x*b + pattern[idx].y*a)*step + \
-               cvRound(pattern[idx].x*a - pattern[idx].y*b)]
-#else
     float x, y;
     int ix, iy;
+#if 1
+    #define GET_VALUE(idx) \
+           (x = pattern[idx].x*a - pattern[idx].y*b, \
+            y = pattern[idx].x*b + pattern[idx].y*a, \
+            ix = cvRound(x), \
+            iy = cvRound(y), \
+            *(center + iy*step + ix) )
+#else
     #define GET_VALUE(idx) \
         (x = pattern[idx].x*a - pattern[idx].y*b, \
         y = pattern[idx].x*b + pattern[idx].y*a, \