This commit is a chance to finally rename this function to something sane. Suggestion: `mch_read_input_chars`.

Underscore in `maxlen`: `max_len` is Style Guide compatible.

`ms` doesn't say much about the purpose of this argument. Suggestion: `wait_time_ms`.

I had to look for the definition of `tb_change_cnt` in `typebuf_T`. Suggestion: rename it to `type_buf_change_count`.