Patch 559 : adding of the neuralgas algorithm

Adding of a neuralgas algorithm to the ml module.

Changes
- Added to original source code
- Changed depricated C API to newer C++ API

Probably fixes will still be required.

Bug report: http://code.opencv.org/issues/559
Previous pull request: https://github.com/Itseez/opencv/pull/1174#issuecomment-21403183