Added a namespace and prefixed global variables with "G_" in order to prevent variable shadowing problems.

* Corrected minor typos in comments/function signatures
* Added new details to copyright statement
* Removed unreferenced macros
* Removed the assert statement which was checking the type of the OutputArray triangle
* When returning results using Mat::copyTo instead of Mat::convertTo
* Changed C-style casts to static_casts
* Added division by zero check to distanceFromPointToLine() function
* Updated reference webpages last access dates
* Moved the declaration of the gammaOfA variable outside the while loop in moveAIfLowAndBIfHigh() function for efficiency reasons

Added the C interface function signature and the overloaded minEnclosingTriangle Python function to the documentation.

Changed the return type of cvMinEnclosingTriangle to CVAPI(void). Added the implementation of the function to the min_enclosing_triangle.cpp source file.

- Wrote the documentation for the minEnclosingTriangle function (+1 extra picture depicting a sample output)

Overloaded the minEnclosingTriangle function such that there is an alternative function with the same name which does not require the output parameter ``area''.
Changed the sample source file minarea.cpp to use the overloaded version of the function.
Updated some comments in the min_enclosing_triangle.cpp source file.

Optimised one assert statement in the min_enclosing_triangle.cpp file. Added the minEnclosingTriangle functionality to the existing minarea.cpp sample file.

Added some assert statements to constrain the type of the input and output parameters. Convert the input set of points to vector<Point2f> before passing it to the findMinimumAreaEnclosingTriangle function.

1. The function receives a set of points as input instead of a convex polygon with more than three vertices
2. The convex hull P is computed inside the function
3.1. If the number of vertices of P is greater than three then the algorithm which was implemented before executes
3.2. Otherwise the vertices of the triangle are picked from the vertices of the given polygon and the area computed

- Changed the type of the minEnclosingTriangle function parameters by using proxy classes InputArray/OutputArray instead of std::vector<T>
- Adapted the source code to accommodate this change

- Added the source code for the function in the separate file min_enclosing_triangle.cpp

it conflicts with cv::detail

changed default parameters in CreateERFiltersNM{1,2} functions. They are not needed now in the sample example.

This allows to get rid of the last remaining Ptr<T>::addref calls.

Also changed the static functions to inline, to stop GCC complaining
about unused functions.