Numerous updates:

- Adding horizontal lines back to the menu
- Updating the navigation JS to support these lines
- Fixing bug when the user uses escape to close a submenu
- Updating editable list box to support keyboard navigation for accessibility
- Updated to close the submenu when the user runs the ISTP compliance check
- Correcting the URL of the SPASE schema file
- No longer including empty elements in the SPASE output
- Now pretty printing the SPASE output with 3 space indents
- Updating the variable name option on the variable attributes page to be an input box
- Updating the options in the CDF specs to support keyboard navigation