We're now reparsing tiles when they expire. We're also swapping out buckets atomically to avoid flickering data; i.e. we're displaying the old data as long as we don't have a new parsed bucket for that layer yet. The parsed buckets now live in the *TileData objects rather than in the TileWorker; only partially parsed == pending buckets will remain in the TileWorker. Once they're parsed, they're moved to the *TileData object.
We are also removing the code that is passing the Environment around
and instead, we get now the Environment in the TileData using
Environment::Get().
When processing the job, the work will be temporally registered to
the Environment as "TileWorker_0/0/0" which can be used for logging
in the future. At the end of the job, it gets unregistered
automatically from the Environment.
we are now scoping all file requests to an environment object. The FileSource implementation treats
this as an opaque pointer, but allows canceling all Requests that are associated with that pointer.
This is necessary to abort all file requests that originated from a particular Map object. Aborting
a file request is different from canceling a file request: A canceled request doesn't have its
callback called, while an aborted request will have its callback called with an error, indicating
that the environment is going to be shut down.