The lib/ directory was getting a bit out of hand, so this tries
to organize things a bit so it is easier going forward to locate
the code people want to patch.
This allows us to use the selection in profile components
without the use of Gtk.
We will probably end up renaming this class to SpSelection or
something like that.
This gets started on allowing the user to select a region.
Nothing is yet responding to the changes in selection, but
that can come later.
Ideally, we will truncate (or mark rows invisible/insensitive)
if they do not fall within the selected time region.
This adds a new helper widget SpVisualizerView to simplify using
visualizers from applications using libsysprof-ui-2 such as
Builder.
We can manage the view range, zoom, etc from this widget going
forward.
We need some sort of scale for content, so we will do this with
an overlay for now. However, we will also want something to be
able to do selections in the future.
This still needs some iteration for correctness, but this sort
of gets the ball rolling.
This will make it easier to support installing just sysprof-cli and the
sysprofd helper daemon on systems where GTK is not feasible or necessary.
This does not, however, do that. It simply gets things broken up into
pieces.
