Remove limit from code block in LineStackCreate()
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.