Add headline anchors & table of contents to game page

[salty-horse]

Long game pages, such as Counterfeit Monkey, can take a while to find the part you want.

For example, when I'm debugging tags, the tag section takes a while to scroll to.

It would be nice if the headlines had an ID, so you could link directly to them. Those headers should also have an easy way to copy a "permalink" to them, like in the Python documentation. It would also be nice to have a sidebar with links to all the section on the page, like the current design of Wikipedia.

[salty-horse]

Duplicate of #411