Release 0.7.0

Release 0.7.0

• Breaking change: instead of #[derive(BitFlags)], the macro is now #[bitflags]
  • This allows a long-awaited feature: when a discriminant isn't provided, the macro will choose an unused bit for you.
• You can now create instances of BitFlags without repeating the name: make_bitflags!(MyFlags::{Foo, Bar}) instead of MyFlags::Foo | MyFlags::Bar. Works in a const fn, too!
• Many new APIs that allow working with BitFlags in a const fn despite rustc limitations
• Many improved error messages
• Implementation details do not show up in user documentation anymore
• Breaking change: rename the RawBitFlags trait to BitFlag - there's nothing raw about it
• Breaking change: the not_literal feature doesn't exist, the relevant functionality is now enabled by default - there is no concern about confusing error messages anymore
• Breaking change: the #[repr(u??)] attribute is now required - previously, Rust's default of usize was used, which is a terrible idea for the size of a bitfield
• Breaking change: BitFlags::new is now called from_bits_unchecked - new suggests that this is the main, preferred way of creating BitFlags. This is not the case.
• the value returned by Default::default can now be customized with #[bitflags(default = Foo | Bar)]