Added missing word and link

Based on the keypoints found we have to +extract+ features (linked tutorial which explains how features work in pcl)
Dual quaternion transformation estimation algorithm added
dq renamed to dual_quaternion;
tests added
dual quaternion precision changed to double to pass the tests
Add an overload of pcl::io::savePNGFile().

The new function takes sensor_msgs::Image and saves it as a PNG file.
Currently supported are "rgb8", "mono8", and "mono16" image encodings.
Add PointCloudImageExtractor base class and several implementations.

* PointCloudImageExtractorFromRGBField produced a color image based on
  the data in "rgb" field of a point cloud.
* PointCloudImageExtractorFromNormalField produced a color image based on
  the data in "normal" field of a point cloud.
* PointCloudImageExtractorFromLabelField produced a mono image based on
  the data in "label" field of a point cloud.
* PointCloudImageExtractorFromZField produces a mono image based on the
  "z" field of a point cloud.
* PointCloudImageExtractorFromCurvatureField produces a mono image based on the
  "curvature" field of a point cloud.
* PointCloudImageExtractorFromIntensityField produces a mono image based on the
  "intensity" field of a point cloud.
Add an overload of pcl::io::savePNGFile().

The new function takes a field name and uses appropriate
PointCloudImageExtractor subclass to extract an image from the given
field. Currently supported are "normal", rgb", "label", "z",
"curvature", and "intensity" fields.
Add pcd2png application to the "tools" module.
Add tests for Point Cloud Image Extractors.
whitespaces added to comply with PCL style; small typos fixed
fixed recognition cmake file and added ransac_based recognition headers at old locations which include the headers at the new locations and deprecation warnings.
CMake changes were not included in previous commit.  Now they are
recognition/CMakeLists.txt now installs the old header files along side the new ones.  Only the new header files were installed in the previous commit
Use short file names in Doxygen output

We are reaching the filesystem limit otherwise.
Merge pull request #250 from andersgb1/master

Fixed failed unit test since #212
Partially fixes issue #124
more whitespaces added
Polydata object was only being allocated but the content was not copied.
Thus passing an empty object to renderViewTesselatedSphere.
Merge pull request #255 from arbeitor/master

Polydata object was only being allocated but the content was not copied.
Merge pull request #252 from jpapon/vtk_pointer_fix

Partially fixes issue #124