Require at least CMake 3.16 and clang-10

The CMake change is now explicit. It was implicitly required by later versions of Kokkos.

clang-9 was failing to build the code for quite a while since it did not compile some proper C++17 code.

src/language/CMakeLists.txt

@@ -18,12 +18,3 @@ add_dependencies(PugsLanguage
   PugsLanguageModules
   PugsLanguageUtils
   PugsUtils)
-
-# ------------------- Installation --------------------
-# temporary version workaround
-if(${CMAKE_VERSION} VERSION_LESS "3.13.0")
-  install(TARGETS PugsLanguage
-    RUNTIME DESTINATION bin
-    LIBRARY DESTINATION lib
-    ARCHIVE DESTINATION lib)
-endif()