Cleaned up adaptive bilateral filtering, added support for gaussian interpolation, updated sample and docs

Changed the signature of the minEnclosingTriangle function such that it returns the area automatically. Moreover, the overloaded function was no longer required so it was removed. Sample code, documentation and unit tests were updated correspondingly.

Removed the cvMinEnclosingTriangle function since the C API will be deprecated starting with OpenCV 3.0

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

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.

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

Conflicts:
	modules/core/include/opencv2/core/cuda.hpp
	modules/cudacodec/src/thread.cpp
	modules/cudacodec/src/thread.hpp
	modules/superres/perf/perf_superres.cpp
	modules/superres/src/btv_l1_cuda.cpp
	modules/superres/src/optical_flow.cpp
	modules/videostab/src/global_motion.cpp
	modules/videostab/src/inpainting.cpp
	samples/cpp/stitching_detailed.cpp
	samples/cpp/videostab.cpp
	samples/gpu/stereo_multi.cpp

Updated to new license.

There's some disagreement about the correct formula.
has its supporters, however, for texture analysis, the newly introduced formula became
standard. The commit enables both uses without breaking backward compatibility.

First contributor of this commit was sperrholz.

InputArray is a reference, and references are always constant anyway. Making
it const even causes a GCC warning.

Update on the class to reflect the review. Split the class into virtual and implementation. change of name to LineSegmentDetector, using Input/Output-Arrays, general clean ups.

removed set/get methods from Algorithm (implement owns)
removed GHT_* enumeration