Version 0.10.0-alpha.6

• Renamed crate::types to builder (56c76a6)
• Introduced Builder::new constructor that automatically determines the API endpoint to use (d117841)
• Use newly introduced BoundingBox type for locations parameter (af5513e)
• Use Cow<_>s for possibly borrowed parameters of Builder, so that you can create an "owned" Builder more easily (2b6584b)
• Removed Builder::method and made Builder::endpoint take an HTTP request method (a00aace)
• Removed FilterLevel::Custom variant (d4221de)
• Removed Error::Custom variant (1a2567f)
• Replaced the (defective) TwitterStream::filter constructor with TwitterStream::{follow,track,locations} constructors (2b59ad6, 022b13f)