DOC: fixed readthedocs
ENH: added tic, tac, toc functions
Docstrings in numpydoc format.
Merge pull request #83 from albop/timing

ENH: added tic, tac, toc functions
minor corrections
Merge branch 'master' of https://github.com/QuantEcon/QuantEcon.py into mc_tools
Minor edits in the docstrings
Added "(object)" in graph_tools