Quick python2 -> python3 conversion for a pair of tutorial scripts, until
the next upstream release.
Index: votca/votca-xtp/tutorials/GROMACS/KMC_Methane/change_energy.py
===================================================================
--- votca-xtp/tutorials/GROMACS/KMC_Methane/change_energy.py
+++ votca-xtp/tutorials/GROMACS/KMC_Methane/change_energy.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 
 import lxml.etree as lxml
 import argparse as ap
@@ -17,4 +17,4 @@ for entry in root.iter('job'):
     estat=region.find("E_static").text
     output.find("E_tot").text=estat
 
-print(lxml.tostring(root, pretty_print=True))
+print((lxml.tostring(root, pretty_print=True)))
Index: votca/votca-xtp/tutorials/LAMMPS/KMC_Thiophene/plotting_scripts/xtp_kmc_makemovie_traj.py
===================================================================
--- votca-xtp/tutorials/LAMMPS/KMC_Thiophene/plotting_scripts/xtp_kmc_makemovie_traj.py
+++ votca-xtp/tutorials/LAMMPS/KMC_Thiophene/plotting_scripts/xtp_kmc_makemovie_traj.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import matplotlib as mpl
 from mpl_toolkits.mplot3d import Axes3D
 from mpl_toolkits.mplot3d import proj3d
@@ -23,7 +23,7 @@ class carrier(object):
     def __init__(self):
         carrier.numberofobjects+=1
         self.id=carrier.numberofobjects
-        print("Charge {} has been added".format(self.id))
+        print(("Charge {} has been added".format(self.id)))
         self.t=[]
         self.x=[]
         self.y=[]
@@ -54,8 +54,8 @@ class carrier(object):
         self.color=color   
      
     def info(self):
-        print("Carrier No. ",self.id)                
-        print(self.array())
+        print(("Carrier No. ",self.id))
+        print((self.array()))
 
 
 class carriercollection(object):
@@ -92,7 +92,7 @@ class carriercollection(object):
             self.xinterval=1.2*np.array([np.min(boxsizes[:,0]),np.max(boxsizes[:,1])])
             self.yinterval=1.2*np.array([np.min(boxsizes[:,2]),np.max(boxsizes[:,3])])
             self.zinterval=1.2*np.array([np.min(boxsizes[:,4]),np.max(boxsizes[:,5])])
-            print(self.xinterval,self.yinterval,self.zinterval)
+            print((self.xinterval,self.yinterval,self.zinterval))
     def mergeonto(self,other):
         self.listofcarriers=self.listofcarriers+other.listofcarriers
 
@@ -107,14 +107,14 @@ class carriercollection(object):
         
     def readinfile(self, infile):   
         with open (infile, "rb") as csvfile:
-            print("Opening file {}".format(infile))
+            print(("Opening file {}".format(infile)))
             reader = csv.reader(csvfile, dialect="excel-tab")
             for row in reader:
                 if  reader.line_num>self.steps and self.steps!=False:
                     break
                 if "time" in row[0]:
                     if "charges" in ''.join(row):
-                        print(''.join(row))
+                        print((''.join(row)))
                         m=re.search('\( ([0-9].?) charges \)',''.join(row))
                         noofcharges=int(m.group(1))
                     else:
@@ -128,7 +128,7 @@ class carriercollection(object):
             for carrier in self.listofcarriers:
                 carrier.array()
 
-            print("Found {} charges in file.".format(noofcharges))
+            print(("Found {} charges in file.".format(noofcharges)))
     
 
     def plottimestep(self,time,step):
@@ -162,13 +162,13 @@ class carriercollection(object):
 
         if os.path.isdir(self.foldername+str(i)) and (os.path.isdir(self.foldername+str(i-1)) or (os.path.isdir(self.foldername) and i==1)):
             os.rename(self.foldername+str(i),self.foldername+str(i+1))
-            print("backing up folder {} to {}".format(self.foldername+str(i),self.foldername+str(i+1)))
+            print(("backing up folder {} to {}".format(self.foldername+str(i),self.foldername+str(i+1))))
         if os.path.isdir(self.foldername) and i==0:
             os.rename(self.foldername,self.foldername+str(i+1))
-            print("backing up folder {} to {}".format(self.foldername,self.foldername+str(i+1)))
+            print(("backing up folder {} to {}".format(self.foldername,self.foldername+str(i+1))))
         if i==0:
             os.mkdir(self.foldername)
-            print("creating folder {}".format(self.foldername))
+            print(("creating folder {}".format(self.foldername)))
         elif i>0:
             self.createfolder(i-1)
         else:
@@ -182,9 +182,9 @@ class carriercollection(object):
         os.chdir(self.foldername)
         tmin=self.tmin()
         print(tmin)
-        steps=range(int(length*framerate)+1)
+        steps=list(range(int(length*framerate)+1))
         for step in steps:
-            print("evaluating frame {} of {}.".format(step,length*framerate))
+            print(("evaluating frame {} of {}.".format(step,length*framerate)))
             time=step*tmin/(length*framerate)
             self.plottimestep(time,step)
         command='ffmpeg -i frame_%04d.png {}'.format(filename)