Merge branch 'master' of https://code.ornl.gov/qci/qcor

A better example

```bash

clang++-9 -std=c++11 -Xclang -load -Xclang compiler/clang/libqcor-ast-plugin.so

    -Xclang -add-plugin -Xclang enable-quantum

    -Xclang -plugin-arg-enable-quantum -Xclang accelerator

    -Xclang -plugin-arg-enable-quantum -Xclang tnqvm

    -Xclang -plugin-arg-enable-quantum -Xclang local-ibm

    -Xclang -plugin-arg-enable-quantum -Xclang transform

    -Xclang -plugin-arg-enable-quantum -Xclang circuit-optimizer

    -I /root/.xacc/include/xacc -I /root/.xacc/include/cppmicroservices4

    -I /home/project/qcor/runtime -L /home/project/qcor/build/runtime

    -lqcor -L /root/.xacc/lib -lxacc test.cpp -o test

```

test.cpp looks like this

```cpp

#include "qcor.hpp"

#include <stdio.h>

#include <string>

int main() {

  xacc::Initialize({"--accelerator", "local-ibm"});

  auto future2 = qcor::submit([&](qcor::qpu_handler &qh) {

int main(int argc, char** argv) {

  xacc::Initialize(argc, argv);

  auto future = qcor::submit([&](qcor::qpu_handler &qh) {

    qh.execute([&]() {

      H(0);

      CX(0, 1);

    });

  });

  auto results = future2.get();

  auto results = future.get();

  results->print();

  printf("\n");

}

```

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