first run of futurize -w -f raise
fix doctest for trac #15990
fix rebase error in 3279bdc
fix raise statement autoconvert error

this came from a badly formatted old style raise statement
Merge branch 'develop' into u/wluebbe/ticket/15990

resolve merge conflicts with 6.2.beat7

Conflicts:
  src/sage/categories/homset.py
  src/sage/categories/weyl_groups.py
  src/sage/combinat/finite_state_machine.py
  src/sage/modular/arithgroup/congroup_gammaH.py
  src/sage/quadratic_forms/quadratic_form__equivalence_testing.py
  src/sage/rings/padics/factory.py
  src/sage/schemes/elliptic_curves/ell_curve_isogeny.py
  src/sage/schemes/elliptic_curves/ell_rational_field.py
  src/sage/schemes/elliptic_curves/padic_lseries.py
  src/sage/schemes/generic/morphism.py
Merge branch 'public/ticket/11726' into raise-plus

Conflicts:
	src/sage/rings/polynomial/laurent_polynomial_ring.py
resolve merge conflicts with #11726
Merge branch 'u/jpflori/ticket/15148' into raise-plus

Conflicts:
	src/sage/schemes/hyperelliptic_curves/hyperelliptic_finite_field.py
resolve merge conflict with #15148
Trac #15990: Python 3 preparation: Change syntax of raise statement

Only the modern syntax like {{{raise E(V)}}} and {{{raise
E(V).with_traceback(T)}}} is accepted by Python 3.[[br]]
Almost all cases change {{{raise E, V}}} to {{{raise E(V)}}} where V is
a string.

**TODO**:
* Clarify why the cases {{{with_traceback}}} were omitted in
{{{libfuturize/fixes/raise.py}}}. (Perhaps this belongs to //stage 2//?)

Changes according to {{{lib2to3/fixes/fix_raise.py}}}:
{{{
raise         -> raise
raise E       -> raise E
raise E, V    -> raise E(V)
raise E, V, T -> raise E(V).with_traceback(T)
raise E, None, T -> raise E.with_traceback(T)

raise (((E, E'), E''), E'''), V -> raise E(V)
raise "foo", V, T               -> warns about string exceptions

CAVEATS:
   "raise E, V" will be incorrectly translated if V is an exception
   instance. The correct Python 3 idiom is
       raise E from V
   but since we can't detect instance-hood by syntax alone and since
   any client code would have to be changed as well, we don't automate
   this.
}}}

URL: http://trac.sagemath.org/15990
Reported by: wluebbe
Ticket author(s): Wilfried Luebbe
Reviewer(s): R. Andrew Ohana