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

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

- and the compilation unit
A new normal refinement routine (#996)

A new normal refinement routine (#996)

- and the unit test
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.
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.
fixed issue #964 regarding non uniform distribution  in RandomSample filter (N changes through iterations, and V is not an integer)  (thanks Marc Gronle)
Rewrite of the explanation of what inliers/outliers are and a few minor english corrections
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.
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.
Merge pull request #150 from patmarion/move-pcd-to-png-target

Move pcl_organized_pcd_to_png target because it requires VTK
Merge pull request #149 from jspricke/cmake-flags

A couple of CMake fixes, mostly cflags related
Merge pull request #148 from georgebrindeiro/patch-1

Rewrite of the explanation of what inliers/outliers are and a few minor ...
Merge pull request #135 from georgebrindeiro/patch-3

Changed order of step-by-step explanation so it follows source code
Merge pull request #129 from andersgb1/sample_consensus_prerejective

A new prerejective pose estimation and alignment routine (#940)
Merge pull request #143 from rbrusu/master

Big refactorization of the include headers for pcl_visualization to reduce compile time of VTK header includes.
Merge pull request #122 from andersgb1/master

A new normal refinement routine (#996)
Merge pull request #128 from romainbregier/master

RandomSample fix
Remove unused variables in geometry