convert poems lib to use c++-style header includes

 *_________________________________________________________________________*/

#include "eulerparameters.h"

#include "math.h"

#include <cmath>

using namespace std;

 *_________________________________________________________________________*/

#include "matrixfun.h"

#include <math.h>

#include <cmath>

#include "fastmatrixops.h"

#include <cstdlib>

#include "system.h"

#include "body.h"

#include "joint.h"

#include <math.h>

#include <cmath>

System::System(){

#include <iostream>

#include <fstream>

#include <string>

#include <stdio.h>   

#include <cstdio>   

#include <iomanip>  

#include "poemslist.h"

#include <iostream>

#include <fstream>

#include <string>

#include <stdio.h>   

#include <cstdio>   

#include <iomanip>  

#include <vector>