fix output of enumerate_totallyreal_*

The output of enumerate_totallyreal_fields_prim,
enumerate_totallyreal_fields_all, and enumerate_totallyreal_fields_rel
are in general simply the output of Pari. They should belong to
Sage proper, so that the output can be later used right away.

This patch makes sure that the output of integers are Integers,
and the output that looks like polynomials belong to PolynomialRing
add more fixes for enumerate_totallyreal_*

Introduce a new keyword return_pari_objects that is set
to True by default so that current usage of these functions
is not affected.

Fix documentation and add doctests to the functions to show
the new behavior if return_pari_objects is set to False
merge develop on to ticket #15552
stop counting polynomials twice

The number of polynomials tested was being counted twice.
This fixes the count.
Ensure that value of n=1, m=1 works.

The variable T was being initialized before the special case
n = 1 and m = 1.
fix the documentation for the enumerate_totally_real*
make sure the output for n=1, or m=1 is a sage object

when return_pari_objects is set to False.
doctest for _rel was incorrect
the doctstring syntax is not latex syntax!
Merge remote-tracking branch 'origin/develop' into ticket/15552
Fix order of output for m=1

The output for m=1 was in a different order compared to the output
for m>1. Thanks to Xiaolu Hou for pointing this out to me!
Update Denis Simon's GP scripts to versions of 06/04/2011 (ell.gp)
resp. 13/01/2014 (ellQ.gp, ellcommon.gp, qfsolve.gp, resultant3.gp)
increase bound in precision check in ell.gp
add/fix doctests for simon_two_descent
Merge branch 'develop' into ticket/15552
fix broken documentation build.
added a check for NULL and a doctest.
This is to avoid SEGFAULT due to Coin returning
NULL in getColSolution() if solve() was not called.
Trac #11005: Update Simon's GP scripts

[See #15608 for a list of open simon_two_descent tickets]

Denis Simon has new versions of his scripts (see
[http://www.math.unicaen.fr/~simon/]), these should be updated (see
`src/ext/pari/simon`).

URL: http://trac.sagemath.org/11005
Reported by: cremona
Ticket author(s): Peter Bruin
Reviewer(s): Jeroen Demeyer
Trac #15483: Simon 2-descent gives RuntimeError for an elliptic curve over a quadratic field

[See #15608 for a list of open simon_two_descent tickets]

The following tries to do 2-descent on an elliptic curve over a
quadratic field:
{{{
K.
=QuadraticField(229)
c4=2173-235*(1-s)/2
c6=-124369+15988*(1-s)/2
E=EllipticCurve([-c4/48,-c6/864])
E.simon_two_descent()
}}}
It fails with a `RuntimeError`:
{{{
Traceback (most recent call last):
...
RuntimeError:
  ***   at top-level: ans=bnfellrank(K,[0,0,0,
  ***                     ^--------------------
  ***   in function bnfellrank: ...eqtheta,rnfeq,bbnf];rang=
  ***   bnfell2descent_gen(b
  ***   ^--------------------
  ***   in function bnfell2descent_gen: ...riv,r=nfsqrt(nf,norm(zc))
  ***   [1];if(DEBUGLEVEL_el
  ***   ^--------------------
  ***   array index (1) out of allowed range [none].
An error occurred while running Simon's 2-descent program
}}}
The problem is apparently that the square root of `norm(zc)` (which is
indeed a square) is not computed due to a precision bug; see comment:7
below.

URL: http://trac.sagemath.org/15483
Reported by: pbruin
Ticket author(s): Peter Bruin
Reviewer(s): Jeroen Demeyer
Trac #15851: fix unhandled segfault in Coin backend

Coin does not properly initialise variables before solving,
leading to get_variables() segfaulting if it is called before
solving. The fix is to check that the pointer returned is not
NULL.

URL: http://trac.sagemath.org/15851
Reported by: dimpase
Ticket author(s): Dmitrii Pasechnik
Reviewer(s): Punarbasu Purkayastha