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.
3083: Not now accepts only one argument
slice of slices simplify
MatrixSlice X[2] -> X[2, :] required
negative indices for MatrixSlice
3083_not:Changes
3083_not:changed args to arg
3083_not: Rectified a mistake of previous commit- arg.arg changed to arg.args
I hope it is correct now.
Incorrect Exception in dsolve()
Travis: install gmp before installing gmpy
added tests
added tests
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.
Extened the named groups module to include information about

whether or not the naemd groups are nilpotent or solvable.
extended_named_groups : some corrections.
Merge pull request #1810 from meclark256/extended_named_groups

Extended the named groups module to include information about nilpotency and solvability