We no longer want RestartAppIfNecessary in the test application
Created SteamControllerTest
Just some final polish before release
Updated for Steamworks.NET 2.0.0's new CallResult API
Flipped the Large Avatar as an example
Created SteamScreenshotsTest
Fixed bug preventing SteamAppsTest callbacks from registering
Created SteamHTTPTest
Updated Steamworks.NET to 2.0.0

No longer using git modules, as Steamworks.NET's directory structure has
changed a fair amount to accommodate editor scripts as well as the
standalone version.
No longer need to store steam_api.dll in the root
Readme updated