tests: allow degraded solutions in the test

Signed-off-by: Ruben Smits <ruben.smits@intermodalics.eu>
drop Eigen2 support since it will be deprecated in Eigen 3.3

also replace the already existing lazyProduct with the noalias as
suggested on http://eigen.tuxfamily.org/dox/Eigen2ToEigen3.html

Signed-off-by: Ruben Smits <ruben.smits@intermodalics.eu>
fix numerous compiler warnings

Signed-off-by: Ruben Smits <ruben.smits@intermodalics.eu>
solvers: replace static const by enum, as defining and assigning static consts in a header is not safe.

Signed-off-by: Ruben Smits <ruben.smits@intermodalics.eu>
solvers: Fix chainjnttojacsolver to use solver interface
Merge pull request #26 from snrkiwi/expand-solveri

solvers: Fix chainjnttojacsolver to use solver interface
Merge remote-tracking branch 'upstream/master' into pu