Review for pull requests on plotting module

[Bharath M R]

Hi,
   My GSoC project will be heavily based on Stefan's pull request for plotting [1]. As the
pull request has not been merged, I have been sending pull requests to his branch.
Can you please help review [2] which deals with complex values plotting and [3] which
deals with adaptive sampling for plotting.

Thanks,
Bharath M R

[1] https://github.com/sympy/sympy/pull/673
[2] https://github.com/Krastanov/sympy/pull/4
[3] https://github.com/Krastanov/sympy/pull/5