Allow for any version of doxygen

The docs appear to build without issues using
the latest version of doxygen, so don't require
the ancient 1.8.6 version.

cmake_modules/FindCurrentDoxygen.cmake

@@ -6,18 +6,11 @@ message(STATUS "Python xml.etree not found, docs disabled.")
     set(IMP_DOXYGEN_EXECUTABLE "${DOXYGEN_EXECUTABLE}" CACHE INTERNAL "")
 else()
 find_package(Doxygen QUIET)
-set(needed_doxygen_version "1.8.6")
 if(DOXYGEN_FOUND)
   imp_get_process_output("Doxygen version" doxygen_version ${CMAKE_BINARY_DIR} COMMAND ${DOXYGEN_EXECUTABLE} --version)
-  if("${doxygen_version}" STREQUAL "${needed_doxygen_version}")
-    message(STATUS "Doxygen is ${DOXYGEN_EXECUTABLE}, version ${doxygen_version}")
-    set(IMP_DOXYGEN_FOUND True CACHE INTERNAL "")
-    set(IMP_DOXYGEN_EXECUTABLE ${DOXYGEN_EXECUTABLE} CACHE INTERNAL "")
-  else()
-    message(STATUS "Wrong doxygen version at ${DOXYGEN_EXECUTABLE}. Found ${doxygen_version}, but needed ${needed_doxygen_version}")
-    set(IMP_DOXYGEN_FOUND False CACHE INTERNAL "")
-    set(IMP_DOXYGEN_EXECUTABLE "not-found" CACHE INTERNAL "")
-  endif()
+  message(STATUS "Doxygen is ${DOXYGEN_EXECUTABLE}, version ${doxygen_version}")
+  set(IMP_DOXYGEN_FOUND True CACHE INTERNAL "")
+  set(IMP_DOXYGEN_EXECUTABLE ${DOXYGEN_EXECUTABLE} CACHE INTERNAL "")
 else()
   message(STATUS "Doxygen not found")
 endif(DOXYGEN_FOUND)