Changed to .NET 4.0
Total refactor; changes were too coupled to split

- Changed CLI arguments
	- Parameters instead of fixed order
	- Support for multiple initial URLs
	- Added -t CLI argument (timeout, in ms)
	- Added -n CLI argument (thread count)
- Split Worker into Worker and UrlProcessor
- Split Context into WorkerContext and UrlProcessingContext
- Better exception handling
- Better status handling
- Download is no longer blocked by pretty printing
	(removed pretty printing in favor of simple status codes)
- Added queue size info; changed status texts