* Fix/recover download flag
why:
The fetch indicator used to control the data download somehow got
lost during re-org.
* Updated chronicles/logger topics
* Reorganised run state flags
why:
The original code used a pair of boolean flags `(stopped,stopThisState)`
which was translated to three states running, stoppedPending, and
stopped. It is currently not clear whether collapsing some states was
correct. So the original logic has been re-stored, albeit wrapped into
directives like `isStopped()` etc.
also:
Moving some function bodies in `worker.nim`
* Moved `reply_data.nim` and `validate_trienode.nim` to sub-directory `fetch_trie`
why:
Only used in `fetch_trie.nim`.
* Move `fetch_*` file and directory objects to `fetch` subdirectory
why:
Only used in `fetch.nim`
* Added start/stop and/or setup/release methods for all sub-modules
why:
good housekeeping
also:
updated getters/setters for ctrl states
updated trace messages
