display better segment length estimates in GUI

[julou]

in order to run Erik's postprocessing on phase contrast data, all the space between segments is currently attached to the neighbouring cells.

this is visually disturbing and curation would be easier if the cells length was shown more accurately

• might be addressed by generating better segment hypotheses
• might be circumvented by post processing the segments length (using Erik's algorithm) before displaying them

[erikvannimwegen]

Explanation:
This is mainly to make the curation easier (i.e. making it easier to spot errors as one scrolls through a movie). It would seem to me that it should be relatively easy to not show the full box (that goes halfway to the next cell) but just show a box with the internal 'best guess' for the size.
Also, if the cell-size refinement (which currently is done in post-processing) were to be included in MoMA, this size could be displayed.