Close cursor + Remove old references to @cursor (it's @state.cursor now) -- Related to #1569
Merge branch 'michel_1569_close_cursor' into next
Check for boost in ./configure

Review 1083 by @tryneus
Closes #1699
Merge branch 'next' into daniel_realtime_message_hub
Adds a missing lock acquisition in message_hub
Fixes a problem with semaphores assuming that yield() preserves ordering.