Squashed 'third_party/eigen/' content from commit 61d72f6

Change-Id: Iccc90fa0b55ab44037f018046d2fcffd90d9d025
git-subtree-dir: third_party/eigen
git-subtree-split: 61d72f6383cfa842868c53e30e087b0258177257
diff --git a/doc/TopicEigenExpressionTemplates.dox b/doc/TopicEigenExpressionTemplates.dox
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+namespace Eigen {
+
+/** \page TopicEigenExpressionTemplates Expression templates in Eigen
+
+
+TODO: write this dox page!
+
+Is linked from the tutorial on arithmetic ops.
+
+*/
+
+}