Changes to support gmpy 1.13 or later, or gmpy2 2.0.0b4 or later.
Improvements to gmpy and gmpy2 fixes.
Remove two extraneous lines from logic to detect gmpy/gmpy2 version.
slice of slices simplify
MatrixSlice X[2] -> X[2, :] required
negative indices for MatrixSlice
Change the colors in the Sphinx documentation

Basically, everything that used to be blue is now green, and everything that
used to be white (text) is now a light gray.  The theme is based off of the
SymPy website, SymPy Live, and SymPy Gamma.

I am not a web designer.  Probably all of this could be done a little bit
better.  Any suggestions are welcome.
Merge pull request #1792 from asmeurer/doc_colors

Change the colors in the Sphinx documentation
Fixing squareroot display issue (#3640)

Calling C.Pow() as was performed prior to commit
4556cfdc26fae8db5adbf10eed72e6305d7aa9a0 to repair issue #3640.
"C.Pow(b, -e)" reintroduced issue #3186, so "evaluate=0" was added
when C.Pow is called to fix #3186 in a different manner:
"C.Pow(b, -e, evaluate=0)".

The following all seem to be correct after this:

>>> sqrt(x)
  ___
╲╱ x
>>> 1 / sqrt(x)
  1
─────
  ___
╲╱ x
>>> pprint (Pow(2,-5,evaluate=0))
1
──
 5
2
>>> print (Pow(2,-5,evaluate=0))
2**(-5)
Merge pull request #1795 from madprime/bugfix/issue_3640

Fixing squareroot display issue (#3640)
Add Madeleine Ball to the AUTHORS/aboutus. Welcome to SymPy!
Travis: install gmp before installing gmpy
Merge pull request #1787 from mrocklin/matrix-slice-of-slice

slice of MatrixSlices simplify
Merge pull request #1805 from certik/travis_gmpy

Travis: install gmp before installing gmpy
Merge pull request #1766 from casevh/master

Single patch for gmpy and gmpy2 support.