Added a function to get a colored cloud of segmentation

- Added a way to copy data from return variable clusters to internal variable clusters_ in order to use it later on.
- Added the implementation of the function getColoredCloud() in class EuclideanClusterExtraction to view a colored cloud of the segmentation result.
Please fix the indention according to the style guide: http://www.pointclouds.org/documentation/advanced/pcl_style_guide.php