Change the internal implementation of some simple headers to make them
more allocator friendly. Also add a constructor method to allow changing
the implementation in the future again.
The headers are:
- Location
- Referrer
- Server
- UserAgent
This change was suggested in [#1104].
BREAKING CHANGES:
- Old code that creates the header structs directly will stop working.
- It's not possible to implement DerefMut for a Cow<'static,str>. Code
that needs to modify header after creation will stop working.
The new macro handles single value headers, list headers, and list
headers with at least one item.
It creates the item for the header and contains its documentation. The
new macro allows handling
more header cases in the future, it will also be possible to include
tests inside the macro.
BREAKING CHANGE: Removed impl_header!() and impl_list_header!() macros,
use new header!() macro.
- Some stray deriving -> derive changes
- use::{mod} -> use::{self}
- fmt.write -> fmt.write_str
This does not catch the last case of fmt.write_str in the
Show impl of a Header Item. This will need to be changed
separately.
