declaration order is not fixed

Error message:
Core.java:97: error: illegal forward reference
    Hamming_normType = NORM_HAMMING,

- better handling of enum arguments
- less merge conflicts

- can be enable separately if needed
- not stable (due storage I/O processing)

* Enabled -Wnarrowing warning

* Fixed type narrowing issues

* Cast python constants

* Use long long for python constants

* Use int for python constants with fallback to long

* Update cv2.cpp

- Use shfl_down, instead of __shfl_down, on warp scan
- Remove race conditions

New computeECC function, and updated findTransformECC function to make gaussian filtering optional (#13837)

* fix for https://github.com/opencv/opencv/issues/12432 with doc and tests

* Added doc string for new parameter.

* Fixes suggested by Alalek for getting around ABI incompatibility.

* Update to docstring, to remove parameter that isn't relevant.

* More updates based on Alalek's usggestions.