Parse meta box and related boxes in in QTFF format

[stefwalter]

In the QTFF format (ie: Quicktime .MOV files) the 'meta' atom
has is a container box instead of a full box. We add a flag
on the stream to indicate this difference in behavior once we
know we are parsing a QTFF format file.

This includes these atoms/boxes:
 * 'keys' which are the named keys in a QTFF 'meta' box
 * 'ilst' which typically follows the 'keys' atom within 'meta'
 * 'data' usually the the contents of an ilst atom

The 'data' box has many data types. Each type is described by the
enumeration dataBox.Types. Only support for those that have a test
file have been implemented so far:

 * UTF8
 * BE_UNSIGNED_INT
 * BE_SIGNED_INT
 * BE_FLOAT32

Tasks to complete before merging:

• Test in my own projects such as https://github.com/stefwalter/refly

closes #309

[stefwalter]

@ DenizUgur The first commit in this pull request is a bug fix to the existing code in the next branch. Would you like a separate pull request for that?

[DenizUgur]

Yes, please. I tend to squash PRs so if it's not strictly relevant to other commits we should make it seperate.

[stefwalter]

Moved the first commit into a separate pull request: #461

[DenizUgur]

Do you have a link to the relevant specification?

[stefwalter]

Do you have a link to the relevant specification?

Sure, here you go: https://developer.apple.com/documentation/quicktime-file-format/

In addition, various portions of the spec are linked in comments from the various box implementations.

I've rebased onto the latest next, and done a quick manual check to see if parsing worked. It does.

When you have an automated test framework, I'd be happy to add tests.

[DenizUgur]

We have tests against File Format Conformance but I'm not sure if there were any QuickTime format files there.

I haven't considered how we'd go on and add tests for other files yet.