Also, documentation & general clean-up:
- remove `gen_char_from`: better served by `sample` or `choose`.
- `gen_bytes` generalised to `gen_vec`.
- `gen_int_range`/`gen_uint_range` merged into `gen_integer_range` and
made to be properly uniformly distributed. Fixes#8644.
Minor adjustments to other functions.
The free-standing functions in f32, f64, i8, i16, i32, i64, u8, u16,
u32, u64, float, int, and uint are replaced with generic functions in
num instead.
If you were previously using any of those functions, just replace them
with the corresponding function with the same name in num.
Note: If you were using a function that corresponds to an operator, use
the operator instead.
Fix a laundry list of warnings involving unused imports that glutted
up compilation output. There are more, but there seems to be some
false positives (where 'remedy' appears to break the build), but this
particular set of fixes seems safe.
