Fix some ARC-specific issues.
Remove redundant ivars for properties.
WindowController: Skip agents and our own process.
Add KLSingleton submodule.
Make controllers singleton
Add TilingController and TilingStrategy protocol
Add Window filtering
Add Application filtering
Add VerticalStrategy
Remove AreaController
Modernize syntax
Fix ARC bugs
Modernize project files
Add HorizontalStrategy
Move sharedInstance method to TilingStrategy protocol
Fix toplevelArea origin