[packagekit] Fine grained groups

[Richard Hughes]

For 0.2.2, in line with the roadmap[1] we need extended groups support.
The current PK architecture allows for fairly course groups, for
instance, System, GNOME and Games. This is less than ideal when you want
to install the "compiz support" group or the "French language" native
backend groups.

It makes little sense to show the user 200 groups to choose from - but
we do need to be able to interact with these collections of software,
for instance, installing the "French language" collection.

I propose two new methods:

SearchCollections(package_id)
Collection(s=collection_enum, b=installed)

InstallCollection(collection_enum)
<does the install of all the sub-packages>

The first would allow to discover what collections a package belongs to,
and the second would allow the user to install the whole group. This
would allow somebody to right click on a package in gpk-application and
a menu would appear. This could be clicked on to install the appropriate
collection.

Note: the collections are enumerated types and so can be translated like
we do the group enums. In this way we can also give them icons.

There's no code, as this needs discussion first. Comments and other
suggestions welcome,

Richard.

[1] http://www.packagekit.org/pk-help.html