Avoid conversion issues when saving the output file when it is set
wrongly. Inform the user with a red box saying "must end in .pdf"
and prevent the user from clicking "convert" before that is fixed.
Combines the validation logic with the already-existing 'update_ui()'
Rename the `global_common` module and `global_common.GlobalCommon` class
to `logic` and `logic.Dangerzone` respectively. Also rename variables
that hold instances of this class.
This change is part of the initial refactor to make the Dangerzone class
handle the core logic of the Dangerzone project.
Originally tied to implment following PEP 589 [1] – TypedDict: Type
Hints for Dictionaries with a Fixed Set of Keys for the Settings
dict.
But this quickly turned out to very challenging without redoing the
code. So we opted instead for using the Any keyword.
[1]: https://peps.python.org/pep-0589/
fixes#144: printing non-ascii characters in a macOS application
opened directly from finder would sometimes lead to an error
message in /var/log/system.log similar to this:
Failed to execute script 'dangerzone' due to unhandled exception:
'ascii' codec can't encode character '\u201c' in position 1:
ordinal not in range(128)
