Squashed 'src/contrib/spirit/' content from commit 51324f7

git-subtree-dir: src/contrib/spirit
git-subtree-split: 51324f7ff5be6a47821c52666221d14d0ee03907
Merge commit '37272680071582a66e1aa05f90c82e7c2a428d21' as 'src/contrib/spirit'
Squashed 'src/contrib/eigen/' content from commit 42856d5

git-subtree-dir: src/contrib/eigen
git-subtree-split: 42856d5e1d3833a3d6111bcebee55ca553149c5a
Merge commit 'de0cb2adfa52df94b19464fb95e8f53e9524f8d6' as 'src/contrib/eigen'