Critical fixes for memory leakage and compatibility

[erdem-kose]

• ONNX protobuf updated,
• Tiny Yolo V2 string allocation valgrind output solved,
• Libonnx source calling converted from <onnx.h> type to "onnx.h" type, because it seeks for /usr/local in some cases
• C99 compatibility increased
• Little endian, big endian compatibility increased and some minor fixes