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

lib/poems/eulerparameters.cpp

@@ -16,7 +16,7 @@
  *_________________________________________________________________________*/
 
 #include "eulerparameters.h"
-#include "math.h"
+#include <cmath>
 
 using namespace std;
 

lib/poems/matrixfun.cpp

@@ -16,7 +16,7 @@
  *_________________________________________________________________________*/
 
 #include "matrixfun.h"
-#include <math.h>
+#include <cmath>
 #include "fastmatrixops.h"
 #include <cstdlib>
 

lib/poems/system.cpp

@@ -19,7 +19,7 @@
 #include "system.h"
 #include "body.h"
 #include "joint.h"
-#include <math.h>
+#include <cmath>
 
 
 System::System(){

lib/poems/system.h

@@ -23,7 +23,7 @@
 #include <iostream>
 #include <fstream>
 #include <string>
-#include <stdio.h>   
+#include <cstdio>   
 #include <iomanip>  
 
 #include "poemslist.h"

lib/poems/workspace.h

@@ -23,7 +23,7 @@
 #include <iostream>
 #include <fstream>
 #include <string>
-#include <stdio.h>   
+#include <cstdio>   
 #include <iomanip>  
 #include <vector>