Fixed path length issue

Fixed an issue with path lengths displaying as 0km on very short (one flowline) paths. It was due to an off-by-one error from my own misinterpretation of one of the flowline properties, which gave the length remaining in the path from the end of a flowline, rather than the beginning. This meant that for some short (~5km), single flowline paths, the total length was being interpreted as 0km instead of 5km. In other cases, the total length was off by the length of the first flowline.

This release also adds several river/stopping feature names.