Emacs: logos version 1.0.0

The logos package provides a simple approach to setting up a “focus mode”. It uses the page-delimiter or the outline together with some commands to move between pages whether narrowing is in effect or not. It also provides some optional aesthetic tweaks which come into effect when the buffer-local logos-focus-mode is enabled. The manual shows how to extend the code to achieve the desired result.

Watch the demo of the original version of logos.el (all my relevant videos since early 2022 use logos).

Package name (GNU ELPA): logos
Official manual: https://protesilaos.com/emacs/logos
Change log: https://protesilaos.com/emacs/logos-changelog
Git repo on SourceHut: https://git.sr.ht/~protesilaos/logos
- Mirrors:
  - GitHub: https://github.com/protesilaos/logos
  - GitLab: https://gitlab.com/protesilaos/logos
Mailing list: https://lists.sr.ht/~protesilaos/logos
Backronyms: ^L Only Generates Ostensible Slides; Logos Optionally Goes through Outline Sections

Below are the release notes.

Revised the fallback condition of the user option logos-outline-regexp-alist (it comes into effect when the logos-outlines-are-pages is non-nil).

The previous value did not account for the buffer-local values of outline-regexp or page-delimiter, nor did it adapt to any changes in their respective values. Instead, it would capture whatever the value was at the time of the symbol’s declaration.

We remove the t condition altogether and instead handle the fallback value internally. Logos will return the current buffer-local value of outline-regexp or page-delimiter, in this order of priority.

Put simply, this has the same intent as before, but works properly.
Introduced a check to guard against a void outline-regexp. The previous value would cause a problem if the outline-regexp had not been set yet. In a typical Emacs session, even on ‘emacs -Q’, the outline-regexp is set in the scratch buffer, so we have a valid value at the outset. However, when the user changes the initial-buffer-choice or opens Emacs directly for a given file, the outline-regexp can be void.

Thanks to Xiaoduan for informing me about this error and for testing my code on how to fix it. This was done via a private channel and is shared with permission.
Implemented the user option logos-hide-cursor. It hides the cursor when logos-focus-mode is enabled. Note that this user option is always buffer-local. Use setq-default to set its default global value (same as with other user options that apply to logos-focus-mode (read the manual)).

Thanks to Marcel Ventosa for suggesting the idea of hiding the cursor. This was done via a private channel and is shared with permission.
Clarified the documentation of logos-focus-mode-extra-functions. It is intended for use by those who are prepared to write custom functions in the spirit of those already used in logos.el to affect the buffer when logos-focus-mode is enabled.
Added the missing autoload cookie to logos-focus-mode. This means that it shows up in the completion candidates of M-x even if the logos library has not been called via require.