the float variant was always shadowed by the int version as
Rect2d is implicitly convertible to Rect.
This swaps things which is fine, as the vector of boxes was always
copied and the computation was done in double.
Test create custom layer in python
* check is contiguos
* Add custom layer test
* Fix test
* Remove assert
* Move assert to pyopencv dnn
* remove assert
* Add unregister
* Fix python2
* proto to bytearray
* Fix data type
Asynchronous API from Intel's Inference Engine (#13694)
* Add forwardAsync for asynchronous mode from Intel's Inference Engine
* Python test for forwardAsync
* Replace Future_Mat to AsyncMat
* Shadow AsyncMat
* Isolate InferRequest callback
* Manage exceptions in Async API of IE
