calculate xAxisOffset based on given height / default

[cheapsteak]

Doesn't seem to fully use the space passed in, resulting in excess whitespace beneath the chart

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The top of the chart is also sometimes a bit crowded when height is ~300

[alex-wilmer]

I expose an option xAxisOffset which is the number of pixels from the bottom of the svg to where the xAxis should start. Playing with height (the total height of the svg) and xAxisOffset gives some room here.. though maybe I should alias xAxisOffset to plotHeight vs totalHeight to make it more sensible for the developer. thoughts?

[cheapsteak]

Since the height is provided, can the graph automatically compute the layout required to fill the space it's given? Spacing/offset seems like something that would be better handled outside the library

Similar to how when laying out an image would usually not involve expanding the image to add whitespace, but rather through css margins

[alex-wilmer]

oh right, yea that should definitely be the default behaviour