- Let's just have one header definining export- and visibility-
macros for Calamares. They are still selected based on the
export flags (*_PRO), just defined in one header instead of two.
- If there is an item with id "" (empty), it is used as the
"no-package-selected" placeholder text.
- Existing code iterated over the abstract model and used the
name and description at the time the model was set -- but
by getting the name and description from the model, only
a single string was obtained instead of the full range
of translations.
- Therefore, when arriving on the page, the "no-package-selected"
information was displayed from the translation that was active
when the model was set.
Instead, extend the non-abstract model so we can find the no-package-
selected item and pass that explicitly to the page.
FIXES#1241
- Using id's as keys in a map orders them indeterminately -- in
practice, alphabetically by key. Switch to a list form so that
the products stick to the order they have in the config file
(which means distro's can list "preferred" versions at top).
Package chooser is a **low density** package selector -- unlike
netinstall which offers a high density tree view -- for picking
zero, one, or more items from a small collection of packages.
This can be used, e.g., for "pick exactly one desktop environment",
"pick zero or more text editors" which can then be installed
by another module. The UI is big and shiny (rather than netinstall's
text-based tree view) and isn't suitable for more than a dozen or
so items.
