Cap amount of footprints to avoid overflowing chart

[erictapen]

There is no easy solution for this, as the length of the diagram is dependent on the screen size.

But there is an mitigation:

Cap the amount of footprints displayable in the whole diagram to a fixed amount and don't render more than that.

That would mean that sometimes we render less footprints than possible and sometimes too many, but in most cases it should be ok.

If footprints are capped, we render the last footprints as three dots (…).

[erictapen]

Implemented the cap in 18c3e9e.

Feel free to ping me if you experience footprint overflow somewhere else.