Fix minor documentation rendering issues

[SirGnip]

• Fix a few minor, isolated documentation rendering issues (code block, function arguments)
• Fixed broken path to gameshell.jpg
• Add table of contents to API and Quick API pages
• Get rid of some make doc warnings

[pvcraven]

These should be up now.

[SirGnip]

The "GameShell" image at the bottom of http://arcade.academy/examples/index.html isn't rendering with proper proportions, which appears to also be throwing off the proportions of the other images in that row. I somehow missed that in my local doc build. I'll take a look.

[pvcraven]

Closed with 2.0 release.