Add PointXYZRGBNormal to PCL_ONLY_CORE_POINT_TYPES

Needed since 96f1c162e7f6dfb2aa6da7c2bd0b4fd22ae615f4
Don't run the Brisk unit test when there is no SSE4.1 available
Simplify Travis build script

- Compile using minimal build flags because of segfaults when using
  processor optimized builds.
Added 3rd party library linking as user code might include our headers
Merge pull request #154 from rbrusu/master

Added 3rd party library linking as user code might include our headers
Merge pull request #153 from jspricke/travis-cmake-test

Fix Travis build
enable rgb extraction when texture saving is enabled
Fix format string bug, thanks clang
Fixed build problem with vtkImageSlice in image_viewer.h
Merge pull request #159 from MOZGIII/master

Fix for #158
Fixed typos, clarified a messy sentence, added wikipedia link
Merge pull request #160 from georgebrindeiro/patch-1

Fixed typos, clarified a messy sentence, added wikipedia link
Merge pull request #155 from whatnick/master

Enable texture extraction in KinfuLS with only the -et flag
Merge pull request #161 from andersgb1/master

Tutorial (and some small fixes) for the prerejective pose estimation routine (#129)