Initial pass at refactoring CDNClient.
So far this only supports requesting a server list.
Keeping the old CDNClient code around as a reference.
Implement connecting to a CS server and downloading depot manifests.
Implement downloading depot chunks.
Add xmldocs for new CDNClient and remove the old code.
Allow specifying the maximum amount of content servers that can be requested.
Fix documentation typo.
Expose the cellid and load values of content servers.
Allow CDNClient to send concurrent commands to a content server.
Merge branch 'cdnclient-refactor'