geom specs

Each geom can depend on a number of javascript variables that have been defined by the Figure object. These are:

• scale - this is a javascript object that has x and y scales for each column of the data frame
• width, height - these are the dimensions of the plotting area. Margins are taken care of! So your axis, for example, can be over [0, width] without having to worry about the bloody margins. We follow the approach in http://bl.ocks.org/1624660
• margin - this is an object with top, right, bottom, left margins. For the basic plots, you shouldn't need to stress about these! As soon as you do anything non standard, these probably get important.