[WIP] DolphinQt: GameList!

This is in a very rudimentary state. There are lots of style violations so don't bother commenting on those, I know I have to fix them. TODO:
 - [ ] Wholesale renaming of all the things that currently are named badly
 - [ ] GameFile should cache FolderName (used in GameTree)
 - [ ] GameTracker does not watch folders (using `QFileSystemWatcher`)
 - [ ] Code for scanning directories is really messy, needs to be fixed (copied wholesale from DolphinWX atm)
 - [ ] Actually delete the `Q...ListItem`s and `GameFile`s when we're done with them
 - [ ] Add more stuff I'm forgetting to this TODO list

No flags are currently visible because that needs #1333 to be merged, so CC @Stevoisiak for that. Also CC @lioncash and @comex for comments on what else needs to be done (read the above first plz :wink:)
And here's the obligatory screenshot:
![dolphinqt-gamelist](https://cloud.githubusercontent.com/assets/2175324/5057891/5b030dfe-6ca7-11e4-8ae4-ae9aead7fdf6.png)

`const std::string&`