Added
- Support for package lists filter based on board
- New dependency is now distro

This is filter for both package lists as well its options to skip them
if they are not compatible with current board. This is primarily
intended to support hardware specific extension in package lists.

No change is required outside of updater-supervisor as package lists are
just skipped and considered as not defined (not existing).

Labels are new generic approach to existing official boolean option.
This removes that option and instead introduces flags that can symbol
anything.

This implementation is just extension of existing one so everything is
till returned all at once. Labels can be matched by name between various
pkglists but that has to be done by user. Here info for labels is
duplicated to every occurrence of that label.

Don't rely on type autodetection

Hidden flag is rarely used so False should be safe default.

Generate correct title and description of pkglist options.

Also polish exceptions

This uses environment variable ROOT_DIR provided by pkgupdater.

This API is obsolete now for some time. If I am not mistaken then Foris
is now using pkglists API calls so we can drop these.

This adds support for URL and support marking. The idea is that we can
have not-translated URL to documentation and also we can separate now
officially supported pkglists from those not supported.

We are already using EUci so those are obsolete.

This should allow caller to possibly handle state when no configuration
is set. No other code should be dirrectly affected because None
evaluates to False in boolean so we are able to still use this function
the same way in conditions. The default value is still False but
representation is None now.

This is to increase security. Although OpenWRT currently does not
support multiple users in default installation and everything runs under
root needless to say we should not write to /tmp which can contain some
bogus files or links to root only writable location by non-root users.

Separate project from updater-ng repository and mark is as 1.0.