Eigen alignment issues (crashes) on 32-bit systems

[tlind]

The entire framework has been tested on a number of 64-bit systems, but not on 32-bit systems. Assertions will fail in srl_laser_segmentation, srl_laser_detectors, srl_nearest_neighbor_tracker etc. due to Eigen/SSE alignment problems, causing the programs to crash.

For more info, see:
http://eigen.tuxfamily.org/dox-devel/group__TopicUnalignedArrayAssert.html

Problematic areas of code:

1. The massive uses of Eigen::Vector2d in std::vector and structure in the packages srl_laser_segmentation and srl_laser_detectors
2. The massive uses of various Eigen components in structure (e.g., Observation) in the package srl_nearest_neighbor_tracker, which are defined in the header file srl_nearest_neighbor_tracker/base/defs.h of the package.
3. Probably also in spencer_social_relations