GitBolt 0.9.3

A fix for Settings crashing GitBolt, and less padding around the
toolbar's Commit and Stash buttons in light mode.

Fixed

• Settings could crash GitBolt once a repository had been opened,
  in every release since 0.9.0; on macOS it crashed every time. Tools →
  Settings, Plugins → Plugin Manager and the Preferences shortcut
  (Cmd+, on macOS) all open that dialog. Settings lists the menu
  commands for its Shortcuts page, and that list, taken at startup,
  included the entries of File → Recent Repositories. Opening a
  repository rebuilds that menu, deleting those entries, and Settings
  then read the deleted entries. Recent Repositories is now left out of
  the list (its entries are folders, not commands), and a menu entry
  deleted later is skipped.

Changed

• Toolbar: in light mode (the Light theme, or System with a light
  appearance), Commit and Stash, the two toolbar buttons that show
  their text, had more padding than the icon buttons. On macOS they
  sat 34pt apart, against 25 to 27pt between the icon buttons; they are
  now 25pt apart. The dark theme is unchanged.
• Contributing: contributors now agree once to a contributor
  license agreement (CLA.md) by ticking its box in the pull
  request template. They keep their copyright, and the project can
  publish their contributions under the GPL-3.0 or a license it
  chooses later.
• Development: a new end-to-end test opens Settings after a
  repository opens. It runs GitBolt with a scratch home folder, so a
  crash leaves no crash report behind for the next real launch.