Fancy progress

This PR implements fancy progress tracking:

* Progress bar will automatically be shown if the ETA is more than a second.
* Progress will be displayed visually as a bar and also as a percentage number.
* The progress bar displays the ETA (estimated time of arrival). (Though, I'm using the simplest possible formula to calculate it right now.)
* The progress bar will display how long the simulation took after finishing.
* The width of the progress bar adjusts to the terminal width if Python >= 3.3 is used (otherwise it defaults to 80 characters)
* In an IPython notebook a fancy HTML/Javascript progress bar will be rendered.

This PR is an alternative suggestion to PR #476.
I'm definitely opposed to handling updates to the system clock; if someone updates their system clock (or rolls into daylight savings) during a simulation, I'm okay with their progress bar getting messed up (the simulation itself will continue fine).

I'm cool with just going with `time.time` as long as we test on a Windows machine before merging. 1s resolution should be sufficient, but should try it out to be sure.