Added imutil.hpp/cpp for ImGui utility functions.

private/raid/SModule

@@ -9,6 +9,7 @@ if not hasattr(env, 'Jinja'):
 src_files = Split("""
     application.cpp
     config.cpp
+    imutil.cpp
     fonts.gen.cpp
     stb_image.cpp
 """)

private/raid/imutil.cpp

@@ -0,0 +1,7 @@
+
+#include "raid/imutil.hpp"
+
+namespace raid::impl
+{
+// std::string gFormatBuffer;
+}