Document std::libc::c_void.
Fixed examples

The examples were still using `core::` instead of `std::`
All of the examples needed a `use std::rand;` at the top to compile
Most of the examples had
    `rng = rand::rng();`
instead of
    `let mut rng = rand::rng();`
Add a `mut_split()` method for dividing one `&mut [T]` into two
Convert json Reader to iterators

This is much faster for strings, and eventually when there is a
buffered reader of some sort.

Reading example.json 100 times before was around 1.18s.
After:
- reading from string 0.68s
- reading from file 1.08s (extra time is all in io::Reader)
auto merge of #7690 : kevinmehall/rust/document-c_void, r=huonw

I added documentation for when to use and not to use `c_void`, since it tripped me up when I started. (See issue #7627)
remove unused imports
unnecessarily mutable variables
unused variable
auto merge of #7691 : nikomatsakis/rust/vec-split-method, r=thestinger

I don't think we have this yet. This makes `&mut [T]` much more flexible.

r? @strcat (or whomever)
auto merge of #7693 : korenchkin/rust/fixdoc_rand, r=cmr

All of the examples were still using `core::` instead of `std::` and  needed a `use std::rand;` at the top to compile
Most of the examples had
    `rng = rand::rng();`
instead of
    `let mut rng = rand::rng();`
auto merge of #7704 : glinscott/rust/json_iter, r=erickt

This is much faster for strings, and eventually when there is a
buffered reader of some sort, will be much faster for files.

Reading example.json 100 times before was around 1.18s.
After:
- reading from string 0.68s
- reading from file 1.08s (extra time is all in io::Reader)

Also:
- fixes #7611 - error when parsing strings and we hit EOF
- updates definition of whitespace in json should only be the 4 ascii whitespace chars
auto merge of #7708 : bcully/rust/warnings, r=thestinger

Just getting my feet wet.
Give term.fg() and term.bg() a bool return value
term: Add new function .attr() to toggle terminal attributes

Also add .supports_attr() to test for attribute support without writing
anything to output.

Update .reset() to use sgr0 instead of op.
Highlight rustc's warnings/errors in bold instead of bright white

Clang actually highlights using bold, not using bright white. Match
clang on this so our diagnostics are still readable on terminals with a
white background.
Don't re-parse terminfo (twice!) on every compiler diagnostic

Stuff the term::Terminal into TLS to avoid re-parsing for every single
message we want to color.