Reorganize navigation and make the module work better in MATLAB Online
1) Add HelperFunctions/OpenOverview.m, Overview.html, Navigation.mlx and Startup.m
2) Update all instructional and application scripts to include return-to-navigation arrows
3) Add corrections to the README and include Open in MATLAB Online links.
4) Add Data to the path in loasStormData to compensate for files that are missing from the project when it is first loaded
5) Update the project to ignore missing files and include new ones
6) Remove the Navigation folder since its contents have moved into HelperFunctions
7) Add appropriate alt-text to images
