[Responsive, accessible menu with submenus] Based on responsive-nav.js

info.txt

Original responsive menu:
https://github.com/viljamis/responsive-nav.js

Forked to allow for submenus with different class names
https://github.com/samikeijonen/responsive-nav.js/tree/dropdowns
-> See usage instructions

Demo: http://samikeijonen.github.io/responsive-nav.js/demos/multiple-levels/
More info: https://foxland.fi/accessible-multi-level-dropdown-navigation/

CSS Files:
* responsive-nav.css (from responsive-nav.js 1.0.39 by @viljamis)
* styles.css (from multiple-levels folder of forked version) - starting from line 121

Implementation: 
-In header.php, modified the structure of the header nav menu using args in wp_nav_menu() to match the structure required for responsive-nav.js
-In functions.php, enqueued js/responsive-nav.js (forked version) and updated js/navigation.js to initialize the responsive-nav script
-In sass/navigation/_menus.scss, added CSS from files mentioned in previous section
-Updated CSS to match desired styling for the theme