macros 1.1

Added

• different setter pattern, e.g. #[builder(pattern="immutable")]
• private setters, e.g. #[builder(private)]
• additional debug info via env_logger, e.g. RUST_LOG=derive_builder=trace cargo test
• prefixes, e.g. #[builder(setter_prefix="with")]
• field specific overrides
• customize builder name, e.g. #[builder(name="MyBuilder")]

Changed

• migration to macros 1.1
• migration to traditional builder pattern
  i.e. seperate FooBuilder struct to build Foo
  => please refer to the new docs

Fixed

• missing lifetime support #21