Fixes lammps_create_atoms library function and its Python interface variant

The interface of that function has changed and includes two additional
parameters, which haven't been added to the Python interface either.
This showed up by trying to run the simple.py example.

python/lammps.py

@@ -362,14 +362,22 @@ class lammps(object):
   #   e.g. for Python list or NumPy, etc
   #   ditto for gather_atoms() above
 
-  def create_atoms(self,n,id,type,x,v):
+  def create_atoms(self,n,id,type,x,v,image=None,shrinkexceed=False):
     if id:
       id_lmp = (c_int * n)()
       id_lmp[:] = id
-    else: id_lmp = id
+    else:
+      id_lmp = id
+
+    if image:
+      image_lmp = (c_int * n)()
+      image_lmp[:] = image
+    else:
+      image_lmp = image
+
     type_lmp = (c_int * n)()
     type_lmp[:] = type
-    self.lib.lammps_create_atoms(self.lmp,n,id_lmp,type_lmp,x,v)
+    self.lib.lammps_create_atoms(self.lmp,n,id_lmp,type_lmp,x,v,image_lmp,shrinkexceed)
 
   # document this?