Update to use system Eigen

[eggerk]

Needs to build:

• [x] thirdparty
• [x] MapLabMultiarch
• [x] MuMa Multiarch

To be reviewed:

• [x] This PR
• [x] ceres
• [x] eigen_catkin
• [x] aslam basic
• [x] MapLab
• [x] MuMa
• [x] Clean up aslam_install

[fabianbl]

@eggerk Can we merge this now?

[eggerk]

@fabianbl Did you have a successful multiarch build? If so, this should be good to merge

@mfehr @schneith any objections to merging this?

[fabianbl]

@eggerk @mfehr @schneith Last week's multiarch build was successful, I will do another try now to be sure: http://129.132.38.183:8080/view/maplab/job/maplab_multiarch/145/

[eggerk]

For some reasons Jenkins failed checking out this repo. I updated the rosinstall: https://github.com/ethz-asl/aslam_install/pull/117 Hopefully, this will fix it

[fabianbl]

Next try: http://129.132.38.183:8080/view/maplab/job/maplab_multiarch/147/

[fabianbl]

http://129.132.38.183:8080/view/maplab/job/maplab_multiarch/149/

[fabianbl]

@eggerk @mfehr @schneith All builds working fine now, I think we can merge this.