initial layout for dynamic expanding plot divs

[tomkane-dls]

if you clone this and see if it works okay for you. There is currently a placeholder bg colour on the cells so we can see what space they take up.

Ideas for tickets to refine this (I will add on monday morning):

1. either remove axes from the plots, or make sure they do not overflow from the actual data
2. stop the plots from staying small when the page is dragged smaller
3. get the plots to expand into the space as expected
4. cleanup use of aspect ratio so it can be passed to the davidia plots and the plot frame component at the same time
5. stop typing errors when a key is not present, as the empty plot is shown

possibility to think about allowing other numbers of plots (2+) but would take some work