Clean _call_, __call__ becomes _call_, second argment is removed.

I've moved __call__ to _call_, hence all the coercion staff is
done by Map. As disscussed in the ticket 16238, the second argument
is removed (it was supposed to change the output of _call_).
Merge branch 'ticket/16245' into ticket/16238
Corrects stylistic staff in doctests.
replace some cmp parameters by key parameters

cmp parameter of sorted() function and L.sort() method
are gone in python3
Merge branch 'ticket/16245-compose_isogenies' into ticket/16238-isogeny_call

Conflicts:
	src/sage/schemes/elliptic_curves/ell_curve_isogeny.py
Trac 16238: reviewer patch
Trac #16916: fix precision issues in cuspform_lseries()
Trac #16916: avoid precision issues in cuspform_lseries

After the previous patch there were a few cases for which the runtime
error would still happen. It turns out that

    q_expansion(num_coeff).list()

is not always a list of length num_coeff, because trailing zeros are
removed. Instead we have to use

    q_expansion(num_coeff).padded_list()

which will not drop the trailing zeros.
remove tabs
trac #16901: make cython code in OA interruptible
Trac #16238: Correct call convention for isogenies

The method `__call__` of the class `EllipticCurveIsogeny` takes a second
argument `output_base_ring`. It seems weird to me, do you find this is
conventional?

Moreover, this method should be `_call_` in order to make the
functionalities of `Map`  available.

URL: http://trac.sagemath.org/16238
Reported by: sbesnier
Ticket author(s): Sébastien Besnier
Reviewer(s): Peter Bruin
Trac #16853: Replace some cmp parameters by key paramters

The {{{cmp}}} parameter has been removed from {{{sorted()}}} and
{{{List.sort()}}} in python3.

This ticket is part of #16536.

URL: http://trac.sagemath.org/16853
Reported by: aapitzsch
Ticket author(s): André Apitzsch
Reviewer(s): Frédéric Chapoton
Trac #16901: cythonized function in combinatorial designs must be interruptible

Right now, we can not interrupt `MOLS_table`... this is a consequence of
the intensive cythonization.
{{{
sage:
sage: from sage.combinat.designs.latin_squares import MOLS_table
sage: MOLS_table(10000)
       0   1   2   3   4   5   6   7   8   9  10  11  12  13  14  15  16
17  18  19
    ____________________________________________________________________
____________
  0| +oo +oo   1   2   3   4   1   6   7   8   2  10   5  12   4   4  15
16   5  18
 20|   4   5   3  22   7  24   4  26   5  28   4  30  31   5   4   5   8
36   4   5
 40|   7  40   5  42   5   6   4  46   8  48   6   5   5  52   5   6   7
7   5  58
^CException KeyboardInterrupt: KeyboardInterrupt() in
'sage.combinat.designs.orthogonal_arrays_find_recursive.is_available'
ignored
360|   7 360   6   7   7   7   6 366  15  15   7  15   7 372   7  15   7
13   7 378
380|   7  12   7 382  15  15   7  15   7 388   7  16   7   7   7   7   8
396   7   7
400|  15 400   7  15  11   8   7  15   8 408   7  13   8  12  10   9  18
15   7 418
^CException KeyboardInterrupt: KeyboardInterrupt() in
'sage.combinat.designs.orthogonal_arrays_find_recursive.is_available'
ignored
...
}}}

We need more `sig_on()`, `sig_off()`.

URL: http://trac.sagemath.org/16901
Reported by: vdelecroix
Ticket author(s): Vincent Delecroix
Reviewer(s): Nathann Cohen
Trac #16916: cuspform_lseries() method for a new form has precision issues

{{{
sage: f = Newforms(67, names='a')[0]
sage: L = f.cuspform_lseries()
...
RuntimeError: Unable to create L-series, due to precision or other
limits in PARI.
}}}

This is because the field {{{prec}}} is used both for the numerical
precision ''and'' for the number of coefficients computed.

Since the L-functions class has a {{{num_coeffs()}}} method, the proper
thing is to use that to know how many coefficients to compute.

URL: http://trac.sagemath.org/16916
Reported by: tornaria
Ticket author(s): Gonzalo Tornaría
Reviewer(s): Michael Neururer