Implement Update. Related to #355
Fix for OS X
Adds info about waiting coros.
Crash if you fail to destruct a sindex token.

This makes a very common error that I was making (failing to destruct a
sindex write token) lead to a crash rather than a deadlock. Hopefully
this will save me some pain.
Fixes a segfault and deletes a sindex_write_token.
Merge branch 'jd_coro_waiting_info' into issue_727
Add cog
Implement a slider
V2 for updates
Add db icon
Thread an interruptor through.
Adds coro print script. Also adds parents to coros.
Prints the parent parameter of the coros.
Makes coros order hierarchically.
Makes coros still show index.
Implement secondary indexes
Fix margin for whole list
disallowed referencing variables from inside secondary index functions (c.f. Issue #718)
Makes erase range work on sindexes in a different way.
Make erase range respect the interruptor.