3D GenMakefile: various improvements

[tahina-pro]

From #172 :

• --makefile now first writes a temporary file (EverParse.Makefile.tmp, or myfile.tmp if --makefile_name myfile was provided) before renaming it to the final name.
• If the value provided with --makefile_name is not an absolute path, then 3D now prepends it with the value provided by --odir
• 3D no longer prints "Module has no output types".

Other improvements:

• If a 3D module A has an entrypoint probe, then 3D now produces A_ExternalAPI.h