Add an adaptive penalty path aggregation

lib/libstereo/CMakeLists.txt

lib/libstereo/include/stereo.hpp

lib/libstereo/include/stereo_types.hpp

lib/libstereo/middlebury/main.cpp

lib/libstereo/src/aggregations/adaptive_penalty.hpp

lib/libstereo/src/array2d.hpp

lib/libstereo/src/cost_aggregation.hpp

lib/libstereo/src/costs/absolute_diff.hpp

lib/libstereo/src/costs/census.hpp

lib/libstereo/src/costs/dual.hpp

lib/libstereo/src/costs/gradient.hpp

lib/libstereo/src/costs/mutual_information.hpp

lib/libstereo/src/dsbase.hpp

lib/libstereo/src/stereo_census_adaptive.cu

lib/libstereo/src/stereo_gradientstree.cu