Conversion PARI t_STR -> Python str should not keep quotes

[Jeroen Demeyer]

This should be without quotes, similar to the difference between repr() and str() of a Python string:

sage: print pari('"hello world"')
"hello world"

[Jeroen Demeyer]

New commits:

​29128c2

Implement conversion PARI t_STR -> Python string

[Peter Bruin]

• The patchbot reports a doctest failure in sage.interfaces.interface.InterfaceElement.__reduce__. I think the quoted version "abc" is the correct output. Probably gen.__reduce__() should use __repr__() instead of __str__().
• It would look better to use %r in the error message that you change in the patch, and actually I would also prefer putting a space after the =, i.e.

  raise TypeError("x (= %r) must be of type t_INT, but is of type %s" % (x, x.type()))
  

(For the second point, maybe we can even remove the type check and rely on PARI to raise an error.)

[git]

Branch pushed to git repo; I updated commit sha1. New commits:

​674fb90	Use repr() for pickling
​1668133	Do not check type in binary(), let PARI raise an error

[Peter Bruin]

Looks good.