do not confuse Eigen3 or beta versions of Eigen3 with Eigen2

cmake/FindEigen2.cmake

diff --git a/cmake/FindEigen2.cmake b/cmake/FindEigen2.cmake
index da95bb0..a834b88 100644
--- a/cmake/FindEigen2.cmake
+++ b/cmake/FindEigen2.cmake
@@ -39,11 +39,11 @@
   set(EIGEN2_MINOR_VERSION "${CMAKE_MATCH_1}")
 
   set(EIGEN2_VERSION ${EIGEN2_WORLD_VERSION}.${EIGEN2_MAJOR_VERSION}.${EIGEN2_MINOR_VERSION})
-  if(${EIGEN2_VERSION} VERSION_LESS ${Eigen2_FIND_VERSION})
+  if((${EIGEN2_WORLD_VERSION} NOTEQUAL 2) OR (${EIGEN2_MAJOR_VERSION} GREATER 10) OR (${EIGEN2_VERSION} VERSION_LESS ${Eigen2_FIND_VERSION}))
     set(EIGEN2_VERSION_OK FALSE)
-  else(${EIGEN2_VERSION} VERSION_LESS ${Eigen2_FIND_VERSION})
+  else()
     set(EIGEN2_VERSION_OK TRUE)
-  endif(${EIGEN2_VERSION} VERSION_LESS ${Eigen2_FIND_VERSION})
+  endif()
 
   if(NOT EIGEN2_VERSION_OK)