More control over Layout composition

[LecrisUT]

Currently there are holoviews.Gridpsace and holoviews.Layout (also holoviews.NdLayout), but it is hard to achieve something in between. For holoviews.Gridpsace there are a few issues:

• matplotlib backend fails when there is only 1 element on y-axis
• I cannot title individual plots and ignore the coordinate axis of the plots

holoviews.Layout has the closest interface but it also has limitations:

• Create a shared legend.
  Currently I use the workaround of enabling the legend of only the last plot and making sure there are dummy curves with nan values
• Control the spacing between elements. (No workarounds found)
• Create a shared xlabel. (No workarounds found)

In a screenshot, I would describe that I am trying to achieve something like this: