[sugar] Activity versioning schema

[Mikus Grinbergs]

>>>> If, as is the current plan, multiple versions of
>>>> an activity can coexist on an XO, ...
> Two use cases:
> 1. I have a journal object. I want to choose which activity to open it with.
> I am presented with a multilevel menu: the top level has all activities
> which open the mime type, the next level has all major versions of those
> activities, the next level minor versions, etc. If click without bothering
> to move over to the sublevels, I get the default version from the sublevel
> of my current menu, which is the starred version (if it exists) or the
> highest version (applied recursively down the sublevels).

I'm sorry, but my mind boggles at the thought of a four-year old 
clicking on a Journal entry and being presented with a palette of 
seventeen different versions of 'TamTam' -- so that he may choose 
which of those versions is appropriate for whatever upgrade the 
adults had made to that XO last week.

mikus