Split view for commit details is now always visible even when empty

[cyrusdaboo]

The latest update causes the commit details view to always be visible even when no commit is selected, wasting vertical space that could be used to show more of the commit history tree. I much preferred the previous version where the commit details was hidden when there was no commit selected. Can we please bring that back, perhaps as a Setting that would give the user the choice of which behavior they want?