feat: suggestion for clock:now

[tarnung]

A quick and dirty implementation for parts of the feature set described in #737

=> clock:now searches for active clocks

I thought that other things than clocks can create "logBookEntries". But maybe i misremember. I could not find any in my demo files.

This pull request does not address the issue #745. Since it does not add to the problem we can go along and refactor later once @schoettl and I what if anything should be done.

[tarnung]

I added a basic indicator for active clocks. It checks for them when parsing the org file and updates their number when clocking in/out.
It currently just turns a button red. This should probably be surplanted by a solution that is more theme aware.

[tarnung]

The indicator can get out of sync when headers with active clocks are deleted. Maybe there's a more robust implementation, maybe this is good enough as it corrects itself on the next file parse.

[munen]

Nice PR!

I thought that other things than clocks can create "logBookEntries". But maybe i misremember. I could not find any in my demo files.

A :LOGBOOK: drawer can also contain a state change for a task. For example updating this task:

* TODO Repeating task
  SCHEDULED: <2019-11-27 Wed +1d>

will become:

* TODO Repeating task
  SCHEDULED: <2019-11-28 Thu +1d>
  :PROPERTIES:
  :LAST_REPEAT: [2021-11-09 Tue 14:39]
  :END:
  :LOGBOOK:
  - State "DONE"       from "TODO"       [2021-11-09 Tue 14:39]
  :END:

Example taken from https://github.com/200ok-ch/organice/blob/master/test_helpers/fixtures/various_todos.org#repeating-task

Relevant Org mode doc: https://orgmode.org/manual/Drawers.html

Having said that, your hasActiveClock implementation looks solid enough that it will only trigger on actual clocks(;

[munen]

I have gone through the code and tested it. It works for me and I like the implementation.

I haven't merged, yet, for this reason: Since the magnifying glass already changes color, I'd say this PR also needs the icon that populates a search with clock:now. Otherwise the magnifying glass indicates something that is actionable, but the user doesn't know what. Alternatively, to get this PR quicker into master, we can remove the color change and add it at a later date.

[tarnung]

this pr is replaced by #751 if the changes over there are accepted

[chasecaleb]

Nice job on this, thanks for implementing @tarnung!