The previous implementation of the code block in LineStackCreate() that
quantifies line overlap used an arbitrary value of 20 as the maximum
number of lines that could overlap in a bin.

During review, Gary questioned the choice.  This ad hoc value was picked
as a high enough limit to carry out the task, given that currently up to
14 lines overlap in a bin.

The previous implementation was also inefficient in that it went over
rfield.fine_lstack map several times to produce the report.

Here, the overlap across rfield.fine_lstack is established ahead of
time, and each fine continuum index in the map is visited only once for
the report.  The ad hoc value of 20 is removed.