Add clang-format file

Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.

LibCore/CUserInfo.cpp

@@ -1,7 +1,7 @@
 #include "CUserInfo.h"
+#include <pwd.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include <pwd.h>
 
 const char* get_current_user_home_path()
 {