Release 7.4.10 (lmn74)

• [lmn_linbo4] Fix KeyError 'diff' when saving an image without the
  diff option: default to False if missing from the POST body. Hide
  the edit button for images that are in an error state.
• [lmn_users] Fix a duplicate "Login" column in the users list
  management view; replaced by the intended "Birthday" column.
  Fix #292.
• [lmn_landingpage] Update landing page (index.html, po/pot, all
  locale .js) to display version 7.4. Merge pull request #290 from
  jolly-jump/patch-1.
• [lmn_setup_wizard] Rebuild all.js.