Adding Notebook; updating scripts for R 3.2.5 and new packages; using relative path and reducing redundant sourcing.
requested to merge Flint-Group/Flint.et.al.2016.Historical.Hydraulic.Bridge.Collapses:master into master
Updates to the original repository such that scripts should work as of 2019-02-22. Functional improvements also made. New notebook with highlights from the journal paper, and supporting scripts. Only loss is due to Google Map's requirement for an API key.