0.3.2
Don't remember the size of balloons of existing comments

They should be calculated automatically based on the content size.
Remember is user wants general comments pane to be shown by default
Fix default size for show-comments balloon

AbstractTreeBuilder is async and is too complex for the simple task
that we have. So don't use it, just add comments to the standard
TreeModel.
Remember propss of the splitter between commits and general comments