Merge Austin to master

In this pull request:

- Bug fixes
- Tetromino shadow
- Abstract screen class (Game now inherits from this)
- Wall kicks on rotations
- Tons of overhauling of doLineClear, should work really well in all cases now
- Constructors now use initializer lists
- More bug fixes
- Documentation for every. single. method.
- Refactored
- Small style shift
- ???