Release Notes:

- Restore `cmd-shift-d` as 'editor::DuplicateLine' and move
`editor::SelectAllMatches` to `cmd-shift-L`, like in VS Code. The
previous action for `cmd-shift-l`, `editor::SplitSelectionIntoLines`,
has been moved to the sublime base keymap.
- Fixes a panic when using 'editor::SelectAllMatches'  on an empty line.