Allow for displaying more than 3 graph boxes in one row in detail view

[chrispcampbell]

Currently there is a hard coded limit (3) on the number of graph boxes that can appear in a row in the detail view in a model-check report. The reason for the limit was because the model-check interface was originally designed around the most basic use case of showing 3 different scenarios for each dataset (at default, at min, at max). Now we have use cases that would benefit from being able to show more than 3 (like 7 or 8) boxes in a single row.

As part of fixing this, I will be removing the font-size: 1vw trick to make the UI scale proportional to the browser window width. This was an OK solution a long time ago, but it prevents browser zoom from working properly. Additionally the layout for the detail view is currently set up to prevent horizontal scroll (an artifact of the previous limit of 3 items per row). Now that we will allow for any number of boxes per row, we should fix up the CSS so that horizontal scroll works correctly.

[chrispcampbell]

To better support the case where a row has many items (causing the horizontal scrollbar to appear), I added a new "Graph Zoom" slider that allows for scaling the comparison graphs without affecting the size of the text. This makes it easier to fit more graphs in the window at once without scrolling (too much).