Made DllImport use a static string for easy renaming of CSteamworks
Updated for Steamworks SDK 1.29a
Updated CSteamworks to 1.7
Removed Linux launch scripts, as they should no longer be needed
Completely revamped the Callback system [API Change]

Callbacks now need to be assigned to a member variable to keep it alive.
There is some backwards compatibility, but it's ill advised as it will
leak memory if used incorrectly.

You now must use Callback<Type_t>.Create(Function); in OnEnable.
And make sure that you are holding a reference to it or the GC will
clean it up before you even get to use it!
Cleaned up #if statements to support new Unity platforms