Added a placement example

#include <qalloc>

// Add a gate b/w q[0] and q[4] which do not connect directly

// to verify the placement algorithm.

__qpu__ void test_xasm(qreg q) {

  using qcor::xasm;

  H(q[0]);

  CX(q[0],q[4]);

  Measure(q[0]);

  Measure(q[4]);

}

// Example: using ibmq_ourense (5 qubits) which has 

// the following connectivity graph:

// 0 -- 1 -- 2

//      |

//      3

//      |

//      4

// Compile: qcor -qpu aer:ibmq_ourense simplePlacement.cpp 

// Make sure to have a valid ~/.ibm_config file.

// Example: 

// key: YOUR_API_KEY

// hub:ibm-q

// group:open

// project:main

// url: https://quantumexperience.ng.bluemix.net

int main() {

  auto q = qalloc(5);

  {

    class test_xasm t(q);

    t.optimize_only = true;

  }

  std::cout << "AFTER PLACEMENT: \n" << quantum::program->toString() << "\n";

}

    !xacc::internal_compiler::qpu->getConnectivity().empty()) {

    irt->apply(program, xacc::internal_compiler::qpu);

  }

  // DEBUG:

  std::cout << "HOWDY:\n" << program->toString() << "\n";

}

std::unordered_map<std::string, int> PassStat::countGates(