Face alignment (#1199)

* This commit will add a new functionality of one millisecond face_alignment to OpenCV.
Face alignment is a computer vision technology for identifying the geometric structure of human faces in digital images.
Given the location and size of a face, it automatically determines the shape
 of the face components such as eyes and nose.
Added following functions :
 1) Application to train a face landmark detector.
 2) Application to detect face landmarks using a trained model.
 3) Application to swap faces using face landmark detection
 4) Application to detect landmarks in a video.
Merged the code with a global facemark API.
Added Doxygen Documentation for the Class created.
Added tutorials for the samples added.
Added visualisations depicting error rate and training time.

Made desired changes

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* face: drop duplicated file

-face_alignmentImpl.hpp
+face_alignmentimpl.hpp

* face: minor refactoring

- replace license headers
- fix usage of "precomp.hpp"