* add Regression module, from eigen1, improved, with doc and unit-test.

* fix .normalized() so that Random().normalized() works; since the return
type became complicated to write down i just let it return an actual
vector, perhaps not optimal.
* add Sparse/CMakeLists.txt. I suppose that it was intentional that it
didn't have CMakeLists, but in <=2.0 releases I'll just manually remove
Sparse.

Eigen/src/Sparse/CMakeLists.txt

@@ -0,0 +1,6 @@
+FILE(GLOB Eigen_Sparse_SRCS "*.h")
+
+INSTALL(FILES 
+  ${Eigen_Sparse_SRCS}
+  DESTINATION ${INCLUDE_INSTALL_DIR}/Eigen/src/Sparse
+  )