update CGAL finder

cmake/FindCGAL.cmake

@@ -26,26 +26,19 @@ endif()
 
 FIND_PACKAGE( CGAL REQUIRED CONFIG
               HINTS $ENV{CGAL_DIR}
-              PATHS "${VS_SEARCH_PATH}/CGAL-4.13"
+                    "${VS_SEARCH_PATH}/CGAL-4.13"
                     "${VS_SEARCH_PATH}/CGAL-4.12"
-                    "${VS_SEARCH_PATH}/CGAL-4.7"
                     /usr/
                     ../../External
-                    "C:/libs/CGAL-3.6"
-                    "C:/Program Files/CGAL-3.5"
-                    "C:/Programme/CGAL-3.5"
-                    "C:/libs/CGAL-3.5"
-                    "C:/Program Files/CGAL-3.4"
-                    "C:/Programme/CGAL-3.4"
-                    "C:/libs/CGAL-3.4"
-                    "C:/Programme/CGAL-3.9"
-                    "C:/Program Files/CGAL-3.9"
-                    "C:/Program Files (x86)/CGAL-3.9"
                     ${module_file_path}/../../../External
               PATH_SUFFIXES lib lib/cmake
               NO_CMAKE_PATH              # if CMAKE_PREFIX_PATH is set we find CGAL 4.12 instead of 4.13. I dont know why that is.
               NO_CMAKE_ENVIRONMENT_PATH) # Set NO_CMAKE_PATH and NO_CMAKE_ENVIRONMENT_PATH to ignore CMAKE_PREFIX_PATH
 
 if (CGAL_FOUND)
-  set(CGAL_BIN_DIRS ${CGAL_BIN_DIR} ${CGAL_BIN_DIR}\..\auxiliary\gmp\lib)
+  set(CGAL_BIN_DIRS ${CGAL_BIN_DIR} ${CGAL_BIN_DIR}/../auxiliary/gmp/lib)
+endif()
+
+if (NOT TARGET CGAL::CGAL)
+  message(FATAL_ERROR "Your CGAL version does not define the CGAL::CGAL target which probably means it is too old")
 endif()
\ No newline at end of file