code: reusing category variable scope
minor refinement

+ defaultCfg for playing with config file
+ on_load replaced with on_activated
code fix: reusing level
db: tasks moved to array for every db types

- flushed at once
- created instantly
- delayed upd ahead
cleanup
+ batch flushing; unfinished

+SQL versioning used.
With batch its not only removed save-at-every-keystroke-overload, but
also made SQL available to store reasonable incremented task's versions.
fix:
fix: accept idented doplets editing
fix: for release
doc updated