Merge pull request #2 from jimcondon/master

Fixed MP4 link in readme

Fixed issue with mdat having 0 size

Merge pull request #1 from crabhit/master

change open mode to 'rb'

Add basic mp4 file handler and testing file.

Allow searching descendants.

Added atom descendant retrieval.

Now cleanly testing timely loading of oversized internal atoms. ATP.

Add support for padded containers.

Fix iterable behaviour for data atoms.

Fix paddings: forgot to account for the fact that we're already skipping the atom header.

Support basic loading of special containers, skipping shitty padding. (Do we need to read it, really?)

Split out special container types, as they're breaking things and will need special treatment later.

Don't skip over containers: their leaf data nodes will handle that for us.