search::KdTree accepts different types of KdTree
fixed const iterator errors (win64)
Fix degenerated rotation axis bug when normal is parallel to x axis.
Remove the redundant scene_search_tree_.
Use depth camera intrinsics unless RGB image registration is active.
Add: ability to add/remove several coordinate systems

This was a requested feature on the mailing list
Fix misuses of std::numeric_limits<T>::min.
Add graph segmentation using random walks

This is an implementation of the algorithm described in "Random Walks
for Image Segmentation" by Leo Grady which works with BGL graphs.
Add unit tests for random walker segmentation
Merge pull request #405 from yangyanli/fix_min_misuses

Fix misuses of std::numeric_limits<T>::min.
Add ${EIGEN_VERSION} to FindEigen.cmake
Add guards to check Eigen version

Random walker needs Eigen::Sparse module, which is available since
version 3.1.0.
Add custom PPA to get latest Eigen for Travis
Fix warnings in common/io.hpp

> io.hpp:275:30: warning: comparison of integers of different signs: 'int' and 'size_type' (aka 'unsigned long') [-Wsign-compare]
Fix warnings in octree/octree_container.h

> octree_container.h:166:7: warning: 'pcl::octree::OctreeContainerEmpty::getSize' hides overloaded virtual function [-Woverloaded-virtual]
> octree_container.h:96:7: note: hidden overloaded virtual function 'pcl::octree::OctreeContainerBase::getSize' declared here: different qualifiers (none vs const)
Fix warnings in sample_consensus/sac_model_circle3d.hpp

> sac_model_circle3d.hpp:283:24: warning: comparison of integers of different signs: 'size_t' (aka 'unsigned long') and 'Index' (aka 'long') [-Wsign-compare]
Fix warnings in sample_consensus/sac_model_registration_2d.hpp

> sac_model_registration_2d.hpp:93:21: warning: unused variable 'pt_tgt' [-Wunused-variable]
Fix warnings in filters/filter_indices.h

> filter_indices.h:186:7: warning: 'pcl::FilterIndices<pcl::PointXYZ>::applyFilter' hides overloaded virtual function [-Woverloaded-virtual]
> filter_indices.h:294:7: warning: 'pcl::FilterIndices<pcl::PCLPointCloud2>::applyFilter' hides overloaded virtual function [-Woverloaded-virtual]
Fix warnings in filters/sampling_surface_normal.hpp

> sampling_surface_normal.hpp:52:30: warning: comparison of integers of different signs: 'unsigned int' and 'int' [-Wsign-compare]
> sampling_surface_normal.hpp:128:13: warning: comparison of integers of different signs: 'const int' and 'unsigned int' [-Wsign-compare]
> sampling_surface_normal.hpp:167:34: warning: comparison of integers of different signs: 'unsigned int' and 'const int' [-Wsign-compare]
Fix warnings in filters/median_filter.hpp

> median_filter.hpp:58:21: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
> median_filter.hpp:59:23: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
> median_filter.hpp:68:45: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]
> median_filter.hpp:69:45: warning: comparison of integers of different signs: 'int' and 'uint32_t' (aka 'unsigned int') [-Wsign-compare]