[fix] DSL: allow scheduled job to send back a reply
[cleanup] minor
[fix] Task-based client DSL: use :task instead of :thread from old DSL for task notification shortcut name
[evol] Task-based client DSL §5 (allow running subtasks in callbacks, implement 'meet' command, and fixed a race btw)
[evol] Task-based client DSL §4 (many fixes, helper, bot stop condition, more logging)
[evol] Task-based client DSL §3 (pass errors and results to next step)
[evol] Task-based client DSL §2 (Subtask and logger)
[evol] added preliminary work on new Task-based client DSL