Instead of potentially falling back to the built-in action that a custom action was intended to override, but (e.g. due to file system reorganizations) now results in a broken link. The extension functionality that is then skipped may result in undesired results, but this may not be immedately obvious to the user (if the extension is not particularly verbose), so some data corruption could occur if this remains undetected.
To avoid duplicating (or somehow extracting) all the built-in actions, simply detect _any_ broken symlink; i.e. offer a superset of the required functionality. So this would also complain about a broken symlink to a non-executable custom (auxiliary) file (rarely used) if that is mistakenly passed as a custom action (unlikely).
Fixes#359
* fix whitespace
* fix spelling
* fix whitespace
* unify headers of tests
* fix some issues in tests, identified by shellcheck
* fix bash completions
bash completion files are not supposed to be executable
* fix some issues identified by shellcheck
Co-authored-by: Ali Karbassi <ali@karbassi.com>
Addons can be placed in subfolders with the same name as the action,
in order to be able to e.g. clone git repos into the TODO_ACTIONS_DIR
rather than having to download addons and manage updates manually.
Closes#120
