Reorganize navigation; make it 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

Author: eszmw

.gitignore

@@ -4,4 +4,6 @@
 *.asv
 
 Data/allStorms.mat
-Data/allStorms.csv
+Data/allStorms.csv
+
+Solutions.zip

Data/loadStormData.mlx

@@ -0,0 +1,13 @@
+function OpenOverview
+% Open the overview file
+locDir = pwd;
+if contains(locDir,filesep+"MATLAB Drive")
+    open("Navigation.mlx")
+else
+    open("Overview.html")
+end
+
+% Close the current script
+close(matlab.desktop.editor.getActive)
+
+end

Derivatives/approximatingDerivatives.mlx

@@ -0,0 +1,10 @@
+function Startup
+% Open the overview file
+locDir = pwd;
+if contains(locDir,filesep+"MATLAB Drive")
+    open("NavigationOverview.mlx")
+else
+    open("Overview.html")
+end
+
+end