[sugar] adding versions to journal/datastore

[Tomeu Vizoso]

Hi Eben and other sugarites,

I'm trying to find a simple way to add some version support to the
journal, but for that I need to know what's the sweetest spot (no pun
intended) between value and complexity.

I'm thinking about making the next notable changes to the UI:

- the journal list shows one line per "interesting" entry. Interesting
entries are tips of branches and a branch is created every time the
user clicks the Keep button or resumes an entry. Activities can also
choose to make a branch in behalf of the user at any moment, for
example just before the user selects "Erase all" in Paint,

- in the detailed view of an entry, all its ancestors are displayed in
a list, including "non-interesting" entries,

- and that's it ;)

Eben: is that too simple? If it's enough, I'll propose an API for it.

Thanks,

Tomeu