add the interaction information
add the interaction information to the docs
Add method to display pmf as LaTeX compiled PDF.
Finish dit.utils.latexarray.to_pdf.

Currently, not importing into dit.utils. This is mostly just a toy
example demonstrating some of the context managers and default opener.
Add ExitStack since 2.6 doesn't support "with A() as B, C() as D: pass".
Tab fix.
Fix validate_probabilities.
Update README.rst
Merge pull request #46 from chebee7i/pmf2pdf

ExitStack and function to display a pmf in a LaTeX array.
Merge pull request #45 from Autoplectic/interaction_information

add the interaction information