Update d-t-m to 83d5bae0 (master branch)

This version does not try to recover from scanning
problems, but simply fails early.
Update Annotator to 7c915a84 (typed-packaging branch)

This version supports falling back to the dummy
document access strategy when scanning with d-t-m fails.

(This allows us to create and reanchor annotations with the
selectors and strategies that don't depend on d-t-m functionality.)
Merge pull request #1642 from hypothesis/1621-strategy-failover

Support document access strategy failover