Merge branch 'master' of github.com:RainerKuemmerle/g2o

Conflicts:
	.travis.yml
Eigen rowmajor compatible

Signed-off-by: Rainer Kuemmerle <kuemmerl@informatik.uni-freiburg.de>
post processing of the Eigen column major patch
cmake_policy for newer versions of cmake
Merge branch 'master' into unit_test

Conflicts:
	g2o/types/slam2d/edge_se2_pointxy_bearing.h
	g2o/types/slam3d/test_isometry3d_mappings.cpp
	g2o/types/slam3d/test_slam3d_jacobian.cpp
	unit_test/slam3d/jacobians_slam3d.cpp