add a link to event/all to event carousel
add event carousel route

This makes it easier to embed it in 3rd party sides
rm redundant instance filter in event.find_by_instance
move event_filter to model.event.all_q
implement event/all filter API for instance activity
use model.Event.all_q in user profile
Merge pull request #793 from xi/feature-subheader-background

subheader background
Merge pull request #794 from xi/feature-event-carousel-morelink

add a link to event/all to event carousel
Merge pull request #796 from xi/feature-event-carousel-route

add event carousel route
Merge pull request #797 from xi/feature-event-stream-api

refactor event stream API
Merge pull request #802 from xi/feature-571-ensure-overlay

ensure we stay in overlay when navigating (link or form)
adapt message model

-  add column "instance"
-  make sender_email and sender_name optional
add find() and all() in model.Message
add message view
add message entity_url
create message events
hide message events from event streams
message tab in dashboard
move send from model to lib
add reply_to in lib.mail