cli/new_worker: fix the debug_port detection
doc/readme: complete the commands list
api/prepare: do not record identical schedule plans

If api.prepare is used in some command line tools to prepare a bunnch
of operations, it is annoying to have as duplicates the identical entries.
cli/unregister-operation: spray some color to ease reading the output
cli/unregister-operation: provide this much-needed command

register-operations has been there for a long time after all, and
field observation shows unregister will be as useful.
cli/list-operations: show the domainn (and reorder attributes in a more useful way)
scheduler: forbid (by default) to use an "every second" rule

This can have some annoying consequences (mostly because
of the input formalism in rework_ui, but having a safety belt there
still make sense).
Added tag 0.12.0 for changeset 7b26dda69a46
remove setup.cfg

We only build pure python on py3 these days.
cli/scheduler: allow to export/import schedule lists

This is done with pickles and the purpose is to make
migrations easier, not long-term archival.
cli/list-scheduled: remove a spurious host entry
inputs/moment: use a better name for the time-delta like operator
doc: small convergence between the readme and the full doc

A torough backport of recent README entries remain
to be done.
tox: use the `extras_require` entry
pkg: really fix the extras_require entry
doc/readme: provide debugging guidance
pkg: do not drag pystuck (heavy depedency) if not explicitly asked
inputs: provide a `moment` input type which accepts lisp expression for dates

The expressions are evaluated at de-serialization time (which means in
practice within the task when the inputs are read).