Typecast Poly to PurePoly in RoofOf._new, fixes #7876
Merge pull request #7831 from KDMOE/docs_of_checksysodesol_and_dsolve

Docs of checksysodesol and dsolve
Refactor and Improvement to Cython autowrap

Lots of changes to c code printing, codegen, and cython autowrap to get
everything to work great with C.

Changes:
- All C code that has a return value now creates a local variable
  "function_name_result" with the datatype of the function (double or
  int). The result is then set equal to variable, and then it's returned
  at the end of the function. This allows multi-line statements to be
  used with a function that has a return value, as this was causing
  problems before with looping and scalars. The printed code is less
  pretty, but will still compile, and a modern compiler should be able
  to optimize this out if it isn't needed.
- New `dereference` kwarg added to `ccode`. This prints the included
  symbols dereferenced `(*a)` instead of `a`. Allows pass by address.
- Cython printing now works. I can't see how it ever did before.
- Matrices are now supported in autowrap.
Support for single indexes in MatrixExpr

This allows MatrixSymbols to be iterated over, and gives a similar
interface to DenseMatrix. MatExpr are treated as row-major order arrays.
This only works if both the matrix shape and index are Integer/int.
Raise NotImplementedError for unequal frequencies. Fixes #7884
Improve Add/Pow._eval_is_imaginary handlers

fixes #4149
fixes #2920
Fixes #7886
Added tests for ccode piecewise printing

Tests for multiple conditions, with and without assignment.
Added test for piecewise w/o assign_to
Added travis testing support for autowrap (i.e. cython and f2py).
Fixed variable naming.
Merge pull request #7865 from hargup/complement_fixes

Fix Intersection Complement simplification
Merge pull request #5 from moorepants/travis-autowrap

Added travis testing support for autowrap (cython,f2py).
Merge pull request #7885 from debugger22/ne-f

Raise NotImplementedError for unequal frequencies. Fixes #7884
Merge pull request #7878 from Tempel/7814_ellipse_symbolic_intersect

Fix #7814: Handle symbols in line-ellipse intersection.
Merge pull request #7888 from jcrist/codeprinting_tests

Added tests for ccode piecewise printing
Added returning of False for UNSAT theory.
Improved pl_true
raise error for non-pi/2 ellipse rotation
Merge pull request #10 from smichr/ellipse

raise error for non-pi ellipse rotation