feat!(journal): periodic & multiple journals

[benlubas]

implements #1471

Features

• Support for multiple journals, and periodic journals
  • Each journal gets a name, start date, time period, and file format string/stategy
  • you can specify period as either days or months + years.
• Ships with a daily, weekly, and monthly journal by default
• users can create their own journals
• all the journal commands now optionally take a journal name. When the name is left out, uses the default journal (configurable, defaults to daily).
• new commands, :Neorg journal previous|current|next <journal_name>
• each journal gets it's own template

Of Note

• looking for feedback on:
  • functionality--does this cover all the cases we want? Does this ship the defaults that we want?
  • user experience/configuration--anything else that should be configurable? Should each journal be able to have its own folder? or should they continue to be in the same overarching folder, with configurable subfolders/the option to not be in a subfolder?
• TOC code is untouched and untested, I think forcing each journal into its own subfolder would make the TOC implementation easier, other suggestions on how to handle it would be welcome
• The breaking change is pretty minimal right now. Templates are now configured differently, and templates files will have a new name. Instead of configuring with template_name = template.norg it's now base_template_name = "template" and templates files will be created on a per-journal basis like: template-daily.norg

[benlubas]

@maxkuzn if you have feedback on the features here that would be great

[vhyrro]

With core.tempus now being the defacto (since 0.10 is required) I can start reviewing this sooner than later. I took a general glance at it and the execution looks solid.

[benlubas]

Had a look at this again. I think the best solution for the journal toc commands will be to make them pattern match for file names so that you get a toc specific to each journal.

I'm fairly sure it's possible to transform the path_format_strategy into a lua pattern iff the path_format_strategy is a string. When that value is a function (which is allowed) we would have to also ask the user to provide some type of filter function that takes a path and tells us if it's a part of the journal.

I think this is a fairly reasonable approach. Let me know if you have thoughts @vhyrro