polys: Allow arbitrary generators in ring() and field()
utilities: Disable timed() tests on Python 2.5
polys: Moved RawMatrix to the top-level
core: Added a docstring to CantSympify
attempt to fix issue 3479 with min( , default_sort_key) and edited test cases
attempt to fix issue 3479 with min( , default_sort_key) and edited test cases
Made new changes
attempt to fix issue 3479 with min() and test cases
Merge branch 'issue3479_trial2' of https://github.com/bgee/sympy into issue3479_trial2
Add Sphinx coverage testing to the coverage_doctest.py tool

This checks if the function is imported into Sphinx. This works by checking
the source from the Sphinx viewcode extension.

This fixes issue 2896.

I still need to add verbose output, and I also need to add some error checking
if the Sphinx docs haven't been built.
Change --no-color to --no-colors

--no-color will still work because OptionParser parses substrings.
Use brown instead of white, in case people have black on white terminals
Add a summary for sphinx

Our current scores are

TOTAL DOCTEST SCORE for sympy: 34% (1984 of 5682)
TOTAL SPHINX SCORE for sympy: 22% (1293 of 5682)

which are not very good.
Tweak colors for coverage_doctest

Sphinx is now printed in gray, so it stands out less.  If the coverage is less
than 50%, the percent is printed in a brighter red.
polys: Fixed vring() and vfield(), and added tests
Fix computation of how many functions are imported into Sphinx

It was computing the inverse.  The actual total is

TOTAL SPHINX SCORE for sympy: 84% (4806 of 5682)

which is not too bad.
polys: Naive and unsafe hashing of PolyElement, ...
Fix coverage_doctest calculations again

The Sphinx percentages should hopefully now be correct.  Assuming they are,
then the actual Sphinx score is 39% (2241 of 5682).

Also start to factor out the colors, so they can more easily be added in
verbose mode.
COLORS!

For coverage_doctest.py -v. If the colors are disabled, print
underlines. Otherwise, they are just too much clutter, because the colors
already delineate the headings just fine.
polys: Added a benchmark for solving 165x165 system