Refactor User#update_last_seen! and User#update_tracked_topics
Update client.zh_CN.yml
 Refactor topics controller

Refactor: 1) TopicsController to reduce code climate complexity.
2) Topic model, addressed comments

fix typo
Russian translation (actual version)
fix fr localization
Reverse positions of buttons on user profile
Put back the user collapsing
some topic-list simplification
Better blockquote button in Markdown editor when non-traditional markdown linebreaks
are enabled.
Oops JSHint again :(
)
further simplification over all, changes include: flatter button style, styling admin table, topic-list style
fixes wrong placement of expect in header integration test
fixes wrong placement of expect in View Topic integration test
Changed breadcrumb dropdowns
Use the debounce parameter instead of hard-coding 100
FIX: weird scroll position on visiting a topic page for the first time (chrome OS X, maybe mobile safari too)
category nav style
require `X-Frame-Options: SAMEORIGIN` for clickjack prevention
Declare rack-protection dependency explicitely
making post-info text brighter, making category nav dropdown text smaller and bold