Use __del__ instead of close

ImageIterator.py

@@ -187,7 +187,7 @@ class ImageIterator():
         self.printer.dec()
         self.printer.print_str("Plotting QOI…")
 
-        qoi_printer.close()
+        qoi_printer.__del__() #MG20190702: Not needed, right?
         commandline  = "gnuplot -e \"set terminal pdf;"
         commandline += " set output '"+qoi_filebasename+".pdf';"
         commandline += " set grid;"

NonlinearSolver.py

@@ -154,7 +154,7 @@ class NonlinearSolver():
         self.printer.dec()
 
         if (self.write_iterations):
-            self.frame_printer.close()
+            self.frame_printer.__del__() #MG20190702: Not needed, right?
             commandline  = "gnuplot -e \"set terminal pdf noenhanced;"
             commandline += " set output '"+self.frame_filebasename+".pdf';"
             commandline += " set key box textcolor variable;"

Problem_ImageRegistration.py

@@ -47,7 +47,7 @@ class ImageRegistrationProblem(Problem):
 
     def __del__(self):
 
-        self.printer.close()
+        self.printer.__del__() #MG20190702: Not needed, right?