Enhanced visualization layout

[lmarini]

Right now they number of colums is fixed and if you only have one it takes up very little space. A couple of options:

• Layout based on number of visualizations. If you one, take up the all tab. If multiple calculate what makes the most sense.
• Allow users to make a viz take up the all tab. They all are small to begin with but there is a "large window" button that makes the visualization take up the whole tab
• Others?