* Support fatal errors in job reports
* WIP: JobReporter and JobInspector
* WIP: JobReportHook and JobReportRef
* Add ChunkError type and asyncRun helper method
* Rename JobReport to JobProgress
* Return a closed channel from Done when the JobProgress is nil
* Comment catchFirstFatal function
* Miscellaneous SourceManager updates
* Own the chunks channel instead of accepting it as an input
* Add Chunks and Wait methods
* Fix bug in Enroll so it actually returns the handle
* Add context.Context parameter to the SourceInitFunc type
* Add SourceManager tests for Run and Wait methods
* Rename man variables to mgr