Separable reduced equations first implementation
matrices: Improved speed of rref() by adding zip_row_op()
polys: Fixed naming convention in solve_lin_sys()
Add more test cases for implicit parsing
Merge pull request #1871 from lidavidm/refactor_implicit_parsing

Refactor implicit parsing
polys: Use faster shallow copy method in PolyElement
Improved docstring and other minor changes
Merge pull request #1881 from smichr/sign

3068_3052: partial resolution of sign/Abs issues
Few changes
make sure all roots are obtained

If the domain permits, compute (then remove duplicates) with all_roots.

Is there a way to remove multiple roots easily so the previous roots
don't have to be recomputed?
printing: Don't import sympy.simplify in printers
printing: Added a trait that abstracts repr() hack
Added correlation(), moment(), cmoment() in rv_interface.py
Fixed whitespaces
Rewrote variance, cmoment and skewness in terms of moment
refactor variance and skewness with cmoment

This requires changing some tests around so that they are less
sensitive to the exact form.

I also had to skip a couple (doc)tests
Added smoment() and refactored skewness()
Added better test-cases, removed bad ones
Merge pull request #1874 from skirpichev/misc

Fix return value for rsolve + misc fixes
Issue #3275 : Added methods to Rotation class for apply to act on states

Methods have been added along with the tests to the Rotation class for qapply to act on the spin states.