pin deps/plotter: per-column x axes, tighter cell gap; docs

docs/USER-GUIDE.md

@@ -90,8 +90,8 @@ Every plot shares **one time window**: panning or zooming in any of them moves t
 sits at the same time in each, and the vertical cursors are the same two times in each. The plots of a split
 row also share **one y range**: the y labels are drawn at the left of the first plot only, the
 horizontal rulers are the same two values in every plot, and a y zoom, pan, fit or fixed range in any of
-them applies to the whole row. Only the bottom row shows the time
-labels. A plot of a split row is named by its row and a letter, `2a` to `2d`: that is what the signals
+them applies to the whole row. The time labels sit under the bottom row, and
+under any row above it whose columns differ from the row below. A plot of a split row is named by its row and a letter, `2a` to `2d`: that is what the signals
 page's **Plot on** buttons and the status line call it, and a signal dragged
 from its badge goes onto the plot under the pointer. The arrangement is saved per source, and a session
 saved before rows could be split opens with one plot per row, as it was.