Remove Mp4 name prefix.
Remove Mp4 name prefix.

This is a crate, so in practise everything can be prefixed by
the mp4parse:: namespace, so we don't need the prefix unless
we want to do something like 'use mp4parse::read_box_header'
directly. Even then the caller could make it clear from context.

kinetiknz/mp4parse-rust,kinetiknz/mp4parse-rust,mozilla/mp4parse-rust