Add surface_matching module.

fix typo which confuses everything

datasets loading module

fixed android warnings

matlab: fix bindings generation for xfeatures2d

This patch fixes Matlab binding generation for modules that are
part of opencv_contrib (xfeatures2d specifically), and are therefore
not located in ${CMAKE_SOURCE_DIR}/modules.

For this, gen_matlab.py script is extended to accept multiple values
for --modules-root argument, and to check for a module's header in
all possible paths. This way, both ${CMAKE_SOURCE_DIR}/modules and
${OPENCV_EXTRA_MODULES_PATH} can be passed as modules root paths,
and main header for xfeatures2d module is correctly located.

Saliency module develop

Line descriptor module

StructuredEdgeDetection to python

RFFeatureGetter* ->  Ptr<RFFeatureGetter> (need this for python wrapper and proper pointer handling)

fixing further nonfree elements

HDR tutorial text removed from edge detection