Disabled conversion warnings - some of them are too silly
fix simulation build, missing glut library
qhull doesn't create output to the stdout
removed a copy of -Wconversion
Move pcl_organized_pcd_to_png target because it requires VTK

pcl_organized_pcd_to_png uses functions from png_io.cpp which has a
VTK dependency.
There is no -O4 in gcc, read the source ;)
Remove setting /wd4800 twice for MSVC
Honor cflags set by the user

In case the user is setting CMAKE_CXX_FLAGS, we assume that he does so
intentionally and don't change it. Needed for cross compilation and
packaging.
Remove SSE branches from CMake build system

Feature branches (like SSE) should be done by the preprocessor to allow
cross compiling.
Rewrite of the explanation of what inliers/outliers are and a few minor english corrections
Changed order of step-by-step explanation so it follows source code

Put RadiusOutlierRemoval before ConditionalRemoval so "the explanation" would follow the order of the source code. Corrected minor typos (it's->its, CondtionalRemoval->ConditionalRemoval), corrected "literalincludes" so the source included comprises complete code blocks.
A new prerejective pose estimation and alignment routine (#940)

A new prerejective pose estimation and alignment routine (#940)

- and the compilation unit
big refactorization of the include headers for pcl_visualization. Major
changes include: forward declarations for most classes used in headers,
and inclusion of real headers (e.g., VTK) in the cpp implementations;
fixes for certain command line tools, apps and examples in PCL that were
not including the headers they were using correctly.
A new normal refinement routine (#996)

A new normal refinement routine (#996)

- and the unit test
fixed issue #964 regarding non uniform distribution  in RandomSample filter (N changes through iterations, and V is not an integer)  (thanks Marc Gronle)
added missing map include that would cause compile failures on older Ubuntus
Remove unused variables in geometry
Remove unused variables in registration
Remove unused variables in io
Remove union warning in octree