Fixing Eigen alignment errors in autotension and zerocal

Maybe of interest to

• @bz
• @cv
• @heather
• @cw

References:

• (general) https://eigen.tuxfamily.org/dox/group__TopicUnalignedArrayAssert.html
• (for autotension) http://eigen.tuxfamily.org/dox-devel/group__TopicStlContainers.html
• (for zerocal) http://eigen.tuxfamily.org/dox-devel/group__TopicStructHavingEigenMembers.html