Merge pull request #1315 from abbat/master

Russian translation (actual version)
Add setting edit_history_visible_to_public to control whether post edits can be viewed by everyone. Uncheck it so only staff users can see edits.
Extract methods to improve flog score of TopicView
FIX: avatars in quotes/oneboxes

Avatars in quotes/oneboxes are still pointing to the old
`/users/:username/avatar(/:size)` route.
So, this adds back the old avatar route for the transition period.
Merge pull request #1323 from ZogStriP/fix-avatars-in-quotes-in-already-cooked-posts

FIX: avatars in quotes/oneboxes
Add oneboxers for popular learning resources
FIX: N+1 query for avatars
Updated Dutch translation
Merge pull request #1326 from sanderdatema/dutch_translation

Updated Dutch translation
Merge pull request #1325 from ZogStriP/fix-n-plus-one-query-for-avatars

FIX: N+1 query for avatars
Merge pull request #1324 from meglio/oneboxers

Add oneboxers for popular learning resources
Generate avatars with transparent background

Generate avatars with transparent background (for .png images) or with white background (for others).
Add warning sign icons to all the delete user buttons
FIX: Respect protocol relative URLs in email styling
Add a confirm modal to Delete All Posts button
FIX: Displaying actions
Merge branch 'master' of github.com:discourse/discourse
FIX: Don't select columns if we don't have to.
FIX: Direct link to Avatar
Screw it, don't choose columns.