libcore: Add read_until to ReaderUtil.
kate: remove export, fail, and move keywords
kate: detect and highlight macro invocations
kate: introduce &rustIdent; entity
kate: detect and highlight regions
kate: detect and highlight core traits
kate: add Self to types
kate: update Rust version
kate: add note about &rustIdent;
kate: consolidate integer suffixes with &rustIntSuf; entity
kate: detect and highlight attributes
kate: restrict char escapes to ones accepted by Rust and highlight hex escapes
kate: allow [] regions to be collapsed
auto merge of #5209 : luqmana/rust/reader, r=graydon
auto merge of #5211 : apasel422/rust/kate, r=graydon

These commits remove some obsolete language features, make some highlighting more correct with respect to the language spec, and introduce highlighting for macros, attributes, core traits, and the new region syntax.
Update region inference for traits so that a method with
explicit self doesn't incorrectly cause the entire trait to
be tagged as being region-parameterized.

Fixes #5224.