Pass grid argument to DC_pair.
Merge branch 'master' of https://github.com/ketch/nodepy

* 'master' of https://github.com/ketch/nodepy:
  Dormand-Prince 8(7) to Prince-Dormand 8(7)
  Shu-Osher implementation
  Return maximum internal amplification factor value at origin.
  DC_pair now accepts chebyshev grids
Merge branch 'master' of https://github.com/ketch/nodepy

* 'master' of https://github.com/ketch/nodepy:
  Add linearized WENO5 semidiscretization.
Add option to step using Butcher form.

Compatibility with Sympy-dev (now we depend on sympy-dev).