Create case.fypp

Author: sbryngelson

src/common/include/case.fypp

@@ -0,0 +1,7 @@
+! This file exists so that Fypp can be run without generating case.fypp files for
+! each target. This is useful when generating documentation, for example. This
+! should also let MFC be built with CMake directly, without invoking mfc.sh.
+
+! For pre-process.
+#:def analytical()
+#:enddef