Removed cmake/ directory with FindEigen3 script

As we now include Eigen as submodule, we're using the one (identical) under 3rdparty/eigen/cmake.

cmake/FindEigen3.cmake

-# - Try to find Eigen3 lib
-#
-# This module supports requiring a minimum version, e.g. you can do
-#   find_package(Eigen3 3.1.2)
-# to require version 3.1.2 or newer of Eigen3.
-#
-# Once done this will define
-#
-#  EIGEN3_FOUND - system has eigen lib with correct version
-#  EIGEN3_INCLUDE_DIR - the eigen include directory
-#  EIGEN3_VERSION - eigen version
-#
-# This module reads hints about search locations from 
-# the following enviroment variables:
-#
-# EIGEN3_ROOT
-# EIGEN3_ROOT_DIR
-
-# Copyright (c) 2006, 2007 Montel Laurent, <montel@kde.org>
-# Copyright (c) 2008, 2009 Gael Guennebaud, <g.gael@free.fr>
-# Copyright (c) 2009 Benoit Jacob <jacob.benoit.1@gmail.com>
-# Redistribution and use is allowed according to the terms of the 2-clause BSD license.
-
-if(NOT Eigen3_FIND_VERSION)
-  if(NOT Eigen3_FIND_VERSION_MAJOR)
-    set(Eigen3_FIND_VERSION_MAJOR 2)
-  endif(NOT Eigen3_FIND_VERSION_MAJOR)
-  if(NOT Eigen3_FIND_VERSION_MINOR)
-    set(Eigen3_FIND_VERSION_MINOR 91)
-  endif(NOT Eigen3_FIND_VERSION_MINOR)
-  if(NOT Eigen3_FIND_VERSION_PATCH)
-    set(Eigen3_FIND_VERSION_PATCH 0)
-  endif(NOT Eigen3_FIND_VERSION_PATCH)
-
-  set(Eigen3_FIND_VERSION "${Eigen3_FIND_VERSION_MAJOR}.${Eigen3_FIND_VERSION_MINOR}.${Eigen3_FIND_VERSION_PATCH}")
-endif(NOT Eigen3_FIND_VERSION)
-
-macro(_eigen3_check_version)
-  file(READ "${EIGEN3_INCLUDE_DIR}/Eigen/src/Core/util/Macros.h" _eigen3_version_header)
-
-  string(REGEX MATCH "define[ \t]+EIGEN_WORLD_VERSION[ \t]+([0-9]+)" _eigen3_world_version_match "${_eigen3_version_header}")
-  set(EIGEN3_WORLD_VERSION "${CMAKE_MATCH_1}")
-  string(REGEX MATCH "define[ \t]+EIGEN_MAJOR_VERSION[ \t]+([0-9]+)" _eigen3_major_version_match "${_eigen3_version_header}")
-  set(EIGEN3_MAJOR_VERSION "${CMAKE_MATCH_1}")
-  string(REGEX MATCH "define[ \t]+EIGEN_MINOR_VERSION[ \t]+([0-9]+)" _eigen3_minor_version_match "${_eigen3_version_header}")
-  set(EIGEN3_MINOR_VERSION "${CMAKE_MATCH_1}")
-
-  set(EIGEN3_VERSION ${EIGEN3_WORLD_VERSION}.${EIGEN3_MAJOR_VERSION}.${EIGEN3_MINOR_VERSION})
-  if(${EIGEN3_VERSION} VERSION_LESS ${Eigen3_FIND_VERSION})
-    set(EIGEN3_VERSION_OK FALSE)
-  else(${EIGEN3_VERSION} VERSION_LESS ${Eigen3_FIND_VERSION})
-    set(EIGEN3_VERSION_OK TRUE)
-  endif(${EIGEN3_VERSION} VERSION_LESS ${Eigen3_FIND_VERSION})
-
-  if(NOT EIGEN3_VERSION_OK)
-
-    message(STATUS "Eigen3 version ${EIGEN3_VERSION} found in ${EIGEN3_INCLUDE_DIR}, "
-                   "but at least version ${Eigen3_FIND_VERSION} is required")
-  endif(NOT EIGEN3_VERSION_OK)
-endmacro(_eigen3_check_version)
-
-if (EIGEN3_INCLUDE_DIR)
-
-  # in cache already
-  _eigen3_check_version()
-  set(EIGEN3_FOUND ${EIGEN3_VERSION_OK})
-
-else (EIGEN3_INCLUDE_DIR)
-  
-  # search first if an Eigen3Config.cmake is available in the system,
-  # if successful this would set EIGEN3_INCLUDE_DIR and the rest of
-  # the script will work as usual
-  find_package(Eigen3 ${Eigen3_FIND_VERSION} NO_MODULE QUIET)
-
-  if(NOT EIGEN3_INCLUDE_DIR)
-    find_path(EIGEN3_INCLUDE_DIR NAMES signature_of_eigen3_matrix_library
-        HINTS
-        ENV EIGEN3_ROOT 
-        ENV EIGEN3_ROOT_DIR
-        PATHS
-        ${CMAKE_INSTALL_PREFIX}/include
-        ${KDE4_INCLUDE_DIR}
-        PATH_SUFFIXES eigen3 eigen
-      )
-  endif(NOT EIGEN3_INCLUDE_DIR)
-
-  if(EIGEN3_INCLUDE_DIR)
-    _eigen3_check_version()
-  endif(EIGEN3_INCLUDE_DIR)
-
-  include(FindPackageHandleStandardArgs)
-  find_package_handle_standard_args(Eigen3 DEFAULT_MSG EIGEN3_INCLUDE_DIR EIGEN3_VERSION_OK)
-
-  mark_as_advanced(EIGEN3_INCLUDE_DIR)
-
-endif(EIGEN3_INCLUDE_DIR)
-