White space between segments

[charlotteburkirts]

The width attribute of a segment is calculated using the first and last index of the segment: at line 106 of frontend/src/components/timeline.js

.attr("width", s.end * xStep - s.start * xStep)

As these indexes are inclusive the width is one step too small. As an example if a face appear on frame 1, 2, and 3 the segment will have a width corresponding of two steps while the face actually appears on 3 frames (three steps).

We propose to change that line to:
.attr("width", (s.end + 1) * xStep - s.start * xStep)