* keep it possible to build for old CC
  * make sure old generations don't come up for the choice
  * remove related version check of old one

fix tests

    pick 54039c2 add python binding and tests for composePanorama

* Implement ASIFT in C++

* '>>' should be '> >' within a nested template

* add a sample for asift usage

* bugfix empty keypoints cause crash

* simpler initialization for mask

* suppress the number of lines

* correct tex document

* type casting

* add descriptorsize for asift

* smaller testdata for asift

* more smaller test data

* add OpenCV short license header

DNN: OpenCL/slice update

* dnn(ocl/slice): make slice kernel VTune friendly

- more unique names
- inline code of copy functions

* dnn(ocl/slice): prefer to spawn more work groups

- even in case with 1D copy
- perf improvement up to 2x of kernel time (due to changed configuration 128x1x1 => 128x32x1)

* dnn(ocl/slice): cache kernel exec info

Adding comment from source code to DetectionOutputLayer class documentation

* Supported convolution with non-const weights

* Fix opencl blobs

* Update tests

…l-clustering

…a-python-binding

* Possibility to set more than one tree for the hierarchical KMeans (default is still 1 tree).

This particularly improves NN retrieval results with binary vectors, allowing better quality
compared to LSH for similar processing time when speed is the criterium.

* Add explanations on the FLANN's hierarchical KMeans for binary data.