GUI Elements Added:
* <button> - a standard button element that allows arbitrary text and allows you to specify an "onclick" event handler to for user actions.
* <menubar> - represents the bar you see at the top of nearly every application. Acts as a container for <menu> & <menuitem> elements.
* <menu> - the DropDown menu element you commonly see such as "File", "Edit", "Help", etc.
* <menuitem> - The actual element that a user will click. This element also supports the "onclick" attribute so you can handle a user's selection.
Docs Added:
Every element has documentation for more understanding. Also, if you want to see a quick demo of what Squishy has to offer you can follow the tutorial found in the docs/ folder.
