Draw events to timeline based on start time and row number #48

Fixed issue #48. One _kind of_ breaking change: I added a row field to the event JSON that helps determine where to draw the block. Details are in the code--I'm going to add some comments to the PR so you can see everything that's going on.
Added a global `_foundry` object. Trying to be a little responsible with all the global vars--we can wrap them up here.