check for @graph keyword in manifest

[christopher-johnson]

See UniversalViewer/universalviewer#385

[edsilv]

Interesting... would it be possible to add your manifest as a test fixture with accompanying test?

https://github.com/viewdir/manifesto/tree/master/test/fixtures

Maybe just testing that it loads correctly. This would also ensure it doesn't break any other tests.

[christopher-johnson]

@edsilv thank you for the reply. I added a test that checks if it loads correctly, and that resources can be read (I reused getManifestType() and getSequenceByIndex(0) ). See lines 117-124 in this file.
@graph_test.txt

All other tests still pass with the change.