Merge Rust, C and C++ SDKs (#4)

* Generate native bindings from rust crate

* Add native instance and runtime statics

* Update README.md

examples/cpp/main.cpp

@@ -0,0 +1,14 @@
+// Copyright (c) Tribufu. All Rights Reserved.
+
+#include <iostream>
+#include <tribufu/api.h>
+
+int main(int argc, char **argv)
+{
+    tribufu_api_initialize();
+    const char *version = tribufu_api_get_user_agent();
+    std::cout << version << std::endl;
+    tribufu_free_string((char *)version);
+    tribufu_api_shutdown();
+    return 0;
+}