Create a reference between the bill text and the change it produces

[mustyoshi]

Even with a minimap function, it will be slightly cumbersome to determine what provision created what change.
So we should add the ability to click a specific provision and then navigate to that location.
This will involve a couple changes

• Allow anchor functionality on both the bill text, and the uscode text when displaying the diffs
  • We should allow users to create anchor links as easily as just hovering over the text
  • Allow updating the URL while the user is scrolling so at any point they can give an anchor link to another person, similar to how congress.gov has started doing things
• Return additional information via the API for each provision that can be used to navigate to the diff
• Add another tooltip or onclick function to each provision that we can make a link for