Merge branch 'u/saraedum/ticket/14482' of http://trac.sagemath.org/sage into ticket/15191
Merge branch 'u/saraedum/ticket/15192' of http://trac.sagemath.org/sage into ticket/15191
Add quotient with remainder and euclidean degree tests to the category of euclidean domains

For such test methods, there has to be a canonical name for the euclidean
degree. Just calling it degree() is very confusing: in the context of Integers
or p-adics, this term does not make too much sense. Additionally, there could
already be a degree() for some elements which happens to be different from the
degree function of the euclidean domain.
Note, that I could not just set euclidean_degree=degree for polynomials because
polynomials (even with coefficients in a field) can have a parent where this is
not the euclidean degree (e.g. in a field K[x]/(f)).
Implement a non-trivial some_elements() for polynomial rings

Before this just returned a single element, the generator. This should probably
be extended much more but at least this makes tests by the category framework
not entirely trivial.
Merge branch 'develop' into ticket/15191-EuclideanDomains_tests

Conflicts:
	src/sage/categories/euclidean_domains.py
	src/sage/rings/polynomial/polynomial_quotient_ring.py
Merge branch 'develop' into ticket/15191

Conflicts:
	src/sage/categories/euclidean_domains.py
Fixed doctests for euclidean_degree
euclidean_degree() is not defined for zero element

Note that it is not enough to check whether a.is_zero() and b.is_zero() since
euclidean rings such as the p-adics might contain actual zero divisors
Fixed documentation doctests
Some minor review tweaks.
Made a note about zero divisors.
trac #16709: IncidenceStructure.packing
trac #16732: make _maxima_init_evaled_ implementations and some bracket translations more robust
The changes here make sure that a few _maxima_init_evaled_ routines process their arguments with
_maxima_init_ rather than just make strings out of them, as well as fix the maxima_string_to_expression parser to properly handle possible nested square brackets.
trac 16XXX shortening some cluster doctests
Merge branch 'public/ticket/euclidean_domains_tests-15191' of ssh://trac.sagemath.org:22/sage into 15191
trac #15191 change bad syntax of 2 input blocks
Merge branch 'u/chapoton/16738' of ssh://trac.sagemath.org:22/sage into 16738
trac #16738 better choice of what to test in reasonable amount of time
trac #16738 removing tests again
Some more review tweaks and fixes.