* fix clippy::unused_io_amount
See related clippy documentation,
but in short some partial reads can occur
in particular with io on the networl.
read_exact/write_all transparently handle such errors.
The fix actually revealed a bug
in 'mp4a' atom parsing, but this is a dangerous change:
Parsing bugs that were transparently ignored
are now failing with error (unattended io eof).
* fix trivial clippy errors
* fix clippy error with always 0 value
* run ci/cd with clippy and latest rust version
Initial effort to reduce or eliminate the use of assertions in the
production code (i.e. not test code). See issue 43 for an example of how
this can cause an application (thread) to panic when reading an unusual
file. Not all of the changes were as simple as returning an Err, since some
functions did not return a Result. Also, the error type used (InvalidData)
is just a catch-all with a message, and in some cases a more refined error
type may be in order.
cargo test passes
