IRV: improve PCP charts layout

[ptormene]

• [ ] when too many indicators are shown, by default the widget is too small to contain the unwrapped table
• [ ] the line for null values might be thicker and the null values might go lower
• [ ] the (displaying n of m) string would probably look better below the table
• [ ] the number of items displayed in the table should depend on the amount of space available in the widget below the chart
• [ ] resizing the widget, the table should not overlap the chart