Better UI for readtheorg, lots of bug fixes

Features and fixes

• Added white background to the table of contents in ReadTheOrg theme #1
• Removed Fontawesome from readtheorg #2
• added depth-agnostic css to deal with arbitrary depth in table-of-contents #3
• Add a title to the top of table of contents just like on readthedocs #4
• fold/unfold items in table-of-contents on click #5