trac 15506: ensure that WeakValueDictionary deletes entries via a list, so that we benefit from Python's trashcan
Merge branch 'ticket/15432' into ticket/15506
15145: add instructions to construct all groups of order 15 or less as fp groups
#15145: review patch.
Fixed failing doctest.
Merge branch 'public/groups/fp_groups-15145' of trac.sagemath.org:sage into public/groups/fp_groups-15145

* 'public/groups/fp_groups-15145' of trac.sagemath.org:sage:
  Fixed failing doctest.
  #15145: review patch.
  15145: add instructions to construct all groups of order 15 or less as fp groups
Fixed not run doctests.
break bullet point first line
Changed "(You will...output.)" line back.
Trac 15506: Add a test (review commit)
Trac #15432: Use a callback with a weak reference to WeakValueDictionary

Following http://bugs.python.org/issue417795, we should probably only
reference the dict weakly from the callback object to avoid unnecessary
circular references.

As we found in http://trac.sagemath.org/ticket/15367#comment:39, if an
object C involved in a reference cycle becomes unreachable as a side
effect of circular GC (e.g., a callback somewhere), the object C will
only be collected by GC in the next round. A non-circularly referenced
object C would have its reference count hit 0 and would be collected
immediately. That is already a good reason to try and avoid circular
references, even now that Python does clean them up eventually.

See also http://trac.sagemath.org/ticket/13394#comment:19 (reasoning the
validity of using a strongly referencing closure should be fine in
theory -- this didn't take into account the practical consideration
above).

URL: http://trac.sagemath.org/15432
Reported by: nbruin
Ticket author(s): Nils Bruin
Reviewer(s): Simon King
Trac #15506: Fix another "recursion depth exceeded" in memory deallocation for weak dictionaries

See: http://trac.sagemath.org/ticket/10963?replyto=174#comment:159 and
follow up for details

This is a follow up to #13394 #15069, and a blocker for #10963.

URL: http://trac.sagemath.org/15506
Reported by: nthiery
Ticket author(s): Nils Bruin
Reviewer(s): Simon King
Trac #15579: Commandline jmol (3-d plots) broken, black window

The following opens jmol with a black window:
{{{
sage: polytopes.n_cube(3).plot()
}}}
This is a regression caused by #14358, which removed the script file to
launch jmol.

URL: http://trac.sagemath.org/15579
Reported by: vbraun
Ticket author(s): Volker Braun
Reviewer(s): Nathann Cohen
Trac #15145: Add instructions for creating fp groups of order 15 or less

Adds documentation and table to constructions/groups giving instructions
on how to create groups of order 15 or less as finitely presented
groups. Documentation refers to commands given by the dependencies
#14998, #14994, #14813, #14791, #15028.

URL: http://trac.sagemath.org/15145
Reported by: dshurbert
Ticket author(s): Davis Shurbert
Reviewer(s): Travis Scrimshaw