p5js/meandering-river - Refactor RiverSegment 'start' determination
p5js/meandering-river - Refactor RiverSegment 'start' determination

* Rather than grabbing hold of the parent's 'end' vector (which due to the algorithm, may be reset)
  - Now it dynamically returns the starting point of the segment, without storing its reference.

NOTE:
- An alternative fix to this is to update the `end` vectors rather than setting them to new vectors.
- I might revisit that during performance evaluation.

brianhonohan/sketchbook,brianhonohan/sketchbook,brianhonohan/sketchbook