another round of dnn optimization (#9011)

* another round of dnn optimization:
* increased malloc alignment across OpenCV from 16 to 64 bytes to make it AVX2 and even AVX-512 friendly
* improved SIMD optimization of pooling layer, optimized average pooling
* cleaned up convolution layer implementation
* made activation layer "attacheable" to all other layers, including fully connected and addition layer.
* fixed bug in the fusion algorithm: "LayerData::consumers" should not be cleared, because it desctibes the topology.
* greatly optimized permutation layer, which improved SSD performance
* parallelized element-wise binary/ternary/... ops (sum, prod, max)

* also, added missing copyrights to many of the layer implementation files

* temporarily disabled (again) the check for intermediate blobs consistency; fixed warnings from various builders

modules/imgproc/src/templmatch.cpp

@@ -135,7 +135,7 @@ void ConvolveBuf::create(Size image_size, Size templ_size)
     const double blockScale = 4.5;
     const int minBlockSize = 256;
 
-    block_size.width = cvRound(result_size.width*blockScale);
+    block_size.width = cvRound(templ_size.width*blockScale);
     block_size.width = std::max( block_size.width, minBlockSize - templ_size.width + 1 );
     block_size.width = std::min( block_size.width, result_size.width );
     block_size.height = cvRound(templ_size.height*blockScale);