When selecting a callback node, show all a list of all of the traces where
that occurred on the right, so that you can select them individually.
Currently this only shows pid/time for on the right, but we'll add another
pane that will show the symbolized backtrace soon.
This provides an area to have augmented functions listing like we have in
the 3-part sysprof view in our current release.
The weighed callgrpah view uses this to show self/total sortable columns
similar to the descendants view.
This is ultimately to replace libsysprof-ui, and will focus on the display
of capture files. Recording will be left to the sysprof application in
terms of UI, and other applications like IDEs will use the
libsysprof-profile API directly along with libsysprof-gtk for visualizing.
