Fix naming conventions for new lints
We actually have an RFC from Oct 2014 specifying naming conventions for lints that is still relevant - https://github.com/rust-lang/rfcs/blob/master/text/0344-conventions-galore.md#lints.
Unfortunately, human memory doesn't work for such prolonged periods of time, so a number of recently added edition-related lints don't follow the conventions.
This PR fixes names for those lints.
Unstable lints, simply renamed:
- `unused_lifetime` -> `unused_lifetimes`
- `absolute_path_not_starting_with_crate` -> `absolute_paths_not_starting_with_crate`
- `unnecessary_extern_crate` -> `unnecessary_extern_crates`
New lints stabilized in the last couple of releases, registered as renamed (old names still work with a warning):
- `single_use_lifetime` -> `single_use_lifetimes`
- `elided_lifetime_in_path` -> `elided_lifetimes_in_paths`
- `bare_trait_object` -> `bare_trait_objects`
- `unstable_name_collision` -> `unstable_name_collisions`
- `unused_doc_comment` -> `unused_doc_comments`
NOT changed, too old to rename:
- `const_err` -> `const_errors`
- `unused_allocation` -> `unused_allocations`
NOT changed, deprecation lints, no need to rename, they are going to be removed anyway:
- `invalid_type_param_default` -> `invalid_type_param_defaults`
- `missing_fragment_specifier` -> `missing_fragment_specifiers`
- `tyvar_behind_raw_pointer` -> `tyvars_behind_raw_pointer`
- `illegal_floating_point_literal_pattern` -> `illegal_floating_point_literal_patterns`
implement the chalk-engine traits
Preliminary implementation for the Chalk traits in rustc. Lots of `panic!()` placeholders to be filled in later.
This is currently blocked on us landing https://github.com/rust-lang-nursery/chalk/pull/131 in chalk and issuing a new release, which should occur later today.
r? @scalexm
cc @leodasvacas
