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.
