Add: tutorial for progressive morphological filter
Fix: allow computation of normals for a subset of input_

This is a quick hack that allows computation of normals for the only provided
indices.
A cleaner solution is more than welcome but due to time constraints I will
commit this to fix the bug for now.
New: KLT Tracking
Refine documentation for `PCLVisualizer::addArrow()` functions
fixes #124, mac os x linker needs to explicity set dynamic_lookup for plugins
Remove "global" from all calls to `addCoordinateSystem`

This makes the tutorial compatible with both PCL <= 1.7.1 and the
current master.

See the discussion on dev list: http://www.pcl-developers.org/pcl-visualizer-demo-cpp-compilation-error-and-solution-td5709431.html
Merge pull request #594 from nizar-sallem/fix_normal_estimation

Fix: computation of normals for a subset of input_
Merge pull request #587 from nizar-sallem/klt

New: KLT Tracking
Merge pull request #612 from taketwo/refine-add-arrow-documentation

Refine documentation for `PCLVisualizer::addArrow()` functions
Merge pull request #613 from fran6co/fix-cloud-composer

Mac os x linker needs to explicity set dynamic_lookup for plugins
Merge pull request #614 from taketwo/fix-pcl-visualizer-tutorial

Remove "global" from all calls to `addCoordinateSystem`
add missing lines of code in bspline_fitting tutorial
Merge pull request #615 from Logrus/bspline-tutorial

add missing lines of code in bspline_fitting tutorial
Fix: make sure point is finite before vicinity search
Merge pull request #617 from nizar-sallem/fix_region_growing

Fix: make sure point is finite before vicinity search
Merge pull request #602 from chambbj/pmf-tutorial

Add: tutorial for progressive morphological filter