Don't focus the prompt when enabling it

This prevents the page from scrolling down on Sphinx docs
Add the Sphinx extension files
Allow autocompletion
Make toolbar align properly
Change fullscreen so it redirects to main site
Allow eval/copy actions
Make header a link to SymPy Live
Use images instead of Unicode arrows
Don't show toolbar on non-highlighted blocks
Add evaluation mode option
Adjust position of output slightly
Add shadow under shell
Make show/hide arrow diagonal
Show banner for Sphinx shell
Fix orientation of settings arrow
Reduce animation duration
Evaluate each statement individually
Fix bug where preexecs weren't being evaluated
Revert to 38bd4a1
Sphinx frontend evaluates each statement separately